The No-Dendro Illusion

In September 2008, Mann et al reported a “significant development” in paleoclimate reconstructions – a “skillfull” reconstruction without tree ring data for over 1300 years.

A skillful EIV reconstruction without tree-ring data is possible even further back, over at least the past 1,300 years, for NH combined land plus ocean temperature (see SI Text). This achievement represents a significant development relative to earlier studies with sparser proxy networks (4) where it was not possible to obtain skillful long-term reconstructions without tree-ring data.

The story was widely covered at the time and the result has been relied upon to marginalize criticism of the reliance of IPCC multiproxy studies on strip bark bulges or tree ring chronologies developed by CRU. Now it turns out that the much vaunted claim to have a “validated” no-dendro reconstruction for the past 1300 years was merely an illusion.

Not only was it an illusion, but recent admissions by Gavin Schmidt show that it foundered on Mann’s much criticized use of the Tiljander sediments – a topic on which the seeming obtuseness of the climate science community to the simplest of issues (e.g. contamination by bridge and agricultural sediments) has mystified third parties over the past two years. Only last month, Schmidt had re-assured readers at Keith Kloor’s that Mann’s misuse of the Tiljander sediments didn’t “matter”. It turns out that it did.

Mann et al 2008

Let’s go back to Mann et al 2008. Claims for its no-dendro reconstruction featured prominently not just in the abstract and conclusions of the article itself, but in associated press releases and promotion.

The abstract to Mann et al 2008 stated:

Recent warmth appears anomalous for at least the past 1,300 years whether or not tree-ring data are used.

The running text stated:

For both methods, we perform reconstructions both with and without dendroclimatic proxies to address any potential sensitivity of our conclusions to issues that have been raised with regard to the reliability of tree-ring data on multicentury time scales (4, 11, 16, 19, 33, 34)…

A skillful EIV reconstruction without tree-ring data is possible even further back, over at least the past 1,300 years, for NH combined land plus ocean temperature (see SI Text). This achievement represents a significant development relative to earlier studies with sparser proxy networks (4) where it was not possible to obtain skillful long-term reconstructions without tree-ring data…

We place greatest confidence in the EIV reconstructions, particularly back to A.D. 700, when a skillful reconstruction as noted earlier is possible without using tree-ring data at all…

Recent warmth exceeds that reconstructed for at least the past 1,800 years in the EIV reconstructions, and this conclusion extends back at least 1,500 years without using tree-ring data.

The point was re-iterated in the caption to its Figure S6.

News Releases for Mann et al 2008
The no-dendro claim of Mann et al 2008 was heavily promoted by Penn State and by the media.

Results of this study without tree-ring data show that for the Northern Hemisphere, the last 10 years are likely unusually warm for not just the past 1,000 as reported in the 1990s paper and others, but for at least another 300 years going back to about A.D. 700 without using tree-ring data. The same conclusion holds back to A.D. 300 if the researchers include tree-ring data.

and continued

“Ten years ago, we could not simply eliminate all the tree-ring data from our network because we did not have enough other proxy climate records to piece together a reliable global record,” said Mann. “With the considerably expanded networks of data now available, we can indeed obtain a reliable long-term record without using tree rings.“

The no-dendro reconstruction was breathlessly reported at realclimate (a post subsequently used as authority by the recent Tamino post):

Now though, the Northern hemisphere land temperature reconstructions without tree rings can go back to 1500 AD or 1000 AD depending on which of two methodologies are used. For the NH land and ocean target, it’s even possible to get a coherent non-tree ring reconstruction back to 700 AD!

ENN reported the no-dendro results pretty much verbatim from the Penn State news release: herehere

Results of this study without tree-ring data show that for the Northern Hemisphere, the last 10 years are likely unusually warm for not just the past 1,000 as reported in the 1990s paper and others, but for at least another 300 years going back to about A.D. 700 without using tree-ring data.

Numerous other news outlets and blogs picked up the “discovery”.

Criticism

Mann et al 2008 was covered in numerous contemporary Climate Audit posts. It was quickly discovered that the heavily publicized no-dendro reconstruction used Tiljander’s Lake Korttajarvi sediments despite warning from Tiljander that the sediments had been heavily contaminated by modern construction and farming, making them totally unsuitable for inclusion in the Mann 2008 algorithm. The contamination was so severe that it resulted in Mann et al using the data upside-down to the climatic interpretation adopted by the original authors for the pre-contamination portion of the series.

The SI showed that Mann et al were aware of Tiljander’s caveats but used the contaminated sediments (upside-down) anyway, thereby compromising the no-dendro reconstruction. They purported to justify the inclusion of Tiljander sediments on the grounds that their inclusion didn’t “matter” because they could “get” a somewhat similar looking stick without the Tiljander sediments. The obvious question was – if they didn’t “matter”, then why use them, given the explicit caveats of the originating author? A question that has never received an answer – only the excuse that the use of the compromised proxies didn’t “matter” – an excuse that is now known to be untrue given the “validation” failure of the no-dendro network without the Tljander sediments.

In January 2009, a short comment by Ross and I on Mann et al was published by PNAS, a comment which included criticism of Mann’s use of the Tiljander sediments despite the caveats. In their response, Mann et al merely stated that our criticism of their use of the Tiljander proxies was “bizarre” and that their SI:

showed that none of our central conclusions relied on their use.

Given the central role of the claim to have a “validated” no-dendro reconstruction, this claim in their Reply now appears to be untrue.

Over the next year and half, Mann’s use of the Tiljander sediments has been a recurring issue over many blogs. A newcomer to the climate blogosphere (AMac), who entered with no particular preconceptions, became extremely frustrated with the obtuseness of the climate community to what seemed to be a black-and-white simple issue and challenged Mann’s defenders. It seemed obvious to him (and to me and to others) that Mann et al had erred in their usage of their proxy and that it was their responsibility to acknowledge and correct the error. AMac was persistent. The more that the “community” arm-waved, the more frustrated he got.

The issue was re-raised most recently at Keith Kloor’s Collide-a-scape in a lengthy thread where Gavin Schmidt argued that critics of Mann et al 2008 were refusing to listen, while Gavin’s critics countered that Gavin’s arguments didn’t make any sense, a position summarized by Lucia on June 18, 2010 with her characteristic lucidityas follows:

So let’s go back to Gavin’s closing complaint:

Thus what we have is not scientists refusing to engage with serious questions, it is the critics refusing to accept the answer.

What seems to have happened in comments here is a scientists gave what appears to be an answer so flawed that people of good faith could easily consider it to be flat out wrong. Critics refuse to accept the answer given by Gavin– a scientist– because the asnwer appears flat out wrong. People who support Gavin are suggesting the critics refusal to accept the answer somehow reflects badly on the critics. We await to see if Gavin returns to explain why his critics should not consider his answer to willis point (b) either flat out wrong or at best, highly misleading. Because currently, Gavin’s claim appears to be contradicted by the evidence he gave to support it.

A month later (July 22), Tamino inadvertently revived the unresolved dispute, by citing the Mann 2008 no-dendro reconstruction in his attack on Andrew Montford’s Hockey Stick Illusion as follows:

As a great deal of other research has shown, you can even reconstruct past temperature without bristlecone pine tree rings, or without any tree ring data at all, [linking to the RC post on Mann et al 2008 here ] resulting in: a hockey stick.

This was not the first time that a realclimate post had invoked the Mann et al 2008 no-dendro stick. They had done so in the Yamal controversy as well:

Tamino’s post sparked renewed discussion of the no-Tilj no-dendro case. In response to a lengthy comment at RC by Judy Curry on July 24, Gavin pointed to a figure in the SI to “Mann et al 2008” showing a no-Tilj no-dendro CPS reconstruction – not mentioning that the figure was not part of the original article, but a correction to the website posted only in Nov 2009 – after Montford’s book was finalized other than the Climategate portion. Gavin:

[Response: Absolutely untrue in all respects. No, really, have you even read these papers? There is no PCA data reduction step used in that paper at all. And this figure shows the difference between reconstructions without any tree ring data (dark and light blue) compared to the full reconstruction (black). (This is a modified figure from the SI in Mann et al (2008) to show the impact of removing 7 questionable proxies and tree ring data together)

This figure is at Mann’s website here, where a change notice dated to November 4, 2009 says:

In the newly corrected figure, we have added the result for NH CPS without both tree-rings *and* the 7 potential “problem series.” Each of the various alternative versions where these sub-networks of proxy data have been excluded fall almost entirely within the uncertainties of the full reconstruction for at least the past 1100 years, while larger discrepancies are observed further back for the reconstruction without either tree-ring data or the 7 series in question, owing to the extreme sparseness of the resulting sub-network.The new figure can be downloaded here (PDF)

Later in the day, Gavin reiterated at RC the claim that there was “no material difference” in results with or without the Tiljander sediments.

The Tiljander stuff is moot since the Mann et al (2008) paper showed both with and without and found no material difference [ in line to 171 on 24 July Comment by D. Robinson — 24 July 2010 @ 8:16 AM]

On July 25, I responded here to some of the issues in Tamino’s post, noting once again the circularity of the original no-dendro no-Tilj argument in an inline comment. The point continued to be contested through the thread, including the following inline comment to Phil Clarke on July 28 ( who was also commenting at realclimate):

In November 2009, just before Climategate, Mann placed a non-Tiljander non-dendro reconstruction on his website. He did not issue a Corrigendum at PNAS nor did he publish a notice of the new information at realclimate. That Mann did so in late 2009 long after the fact did not refute the claim in respect to Mann et al PNAS 2008. It’s very misleading for Gavin to pretend that a website addition in November 2009 was part of the corpus of Mann et al 2008, that should have been considered in CA commentary on Mann et al 2008 in late 2008 (which was what MOntford was reviewing).

This comment was posted at RC by Judy Curry on July 28 occasioning a retort from Gavin who falsely accused Montford of attributing motives to Mann’s failure to present a no-Tilj no-dendro combination (Montford had observed the circularity and had not speculated as to motive). In his inline comment, Schmidt made what, to my knowledge, is the first public notice that the Mann et al 2009 (Science) SI (not Mann et al 2008 PNAS) had reported that the no-dendro reconstruction without the contaminated sediments did not verify prior to 1500. In other words, announcing the demise of the much vaunted “validated” no-dendro reconstruction back for 1300 years. Gavin:

[Response: Pure spin. The additional graph was posted because of inaccurate claims that there was something wrong with the no-dendro reconstruction because of the inclusion of the already-acknowledged-to-be-problematic Tiljander proxies. The sensitivity studies in the original paper didn’t include that the no-dendro/no-Tiljander combination but that does not justify the claims made by Montford that such a combination was impossible or was not included because it undermined the results. Indeed, you can do a no-dendro and no-Tiljander reconstruction with the code that was posted with Mann et al (2008), and that was what was added to the figure I showed. Montford was apparently happy to make up results and conclusions in late 2008 that were just not justified, and for this you give him a pass? Curious. For further information, the no-dendro/no-Tiljander sensitivity test is also part of the SI in Mann et al (2009) (figure S8), where it is noted that it doesn’t validate prior to 1500 AD. Of course if you remove all data that is imperfect, you will end up with no results. But as Salzer et al point out, there is likely to be useful climate information in the tree rings so I wouldn’t throw them out unnecessarily. – gavin]

The bolded sentence should have caught everyone’s attention, but it was mixed in with a number of other contentious issues and passed without further comment.

[Update: On July 30, I responded to Gavin Schmidt’s reference to the CPS reconstruction at Mann’s website in a lengthy CA post here, presenting my own estimate of the no-Tilj no-bristle CPS reconstruction using Mann 2008 methods on the AD1000 proxy network:

This differed dramatically from the image at Mann’s website. I postulated that the difference arose from Luterbacher gridded data as follows:

Mann’s graphics all show the results of spliced reconstructions rather than what you get with proxies going back to AD1000. The provenance of the network used in Mann’s November 2009 revision of a figure in his SI isn’t described as clearly as it might be. My interpretation of the figure is that the network includes 71 Luterbacher gridded European series which use instrumental temperature data. It is my surmise that in its latter portion, the stick-ness of the “new” no_tilj no-dendro reconstruction derives from splicing the Luterbacher gridcell data (using instrumental data) onto the horrible no-dendro reconstruction.

The next day, Phil Clarke re-capped (rather disparagingly) my analysis of the “frozen” AD1000 network at RC as follows:

His contention being that in the various sensitivity tests the combinations were carefully chosen to leave a mix that gave a Hockey Stick. Remove Bristlecones but leave in the inverted Tiljander, exclude Tiljander but add the Bristlecones back in etc. I read this post as an attempt to demonstrate this by rolling his own No-dendro, no-Tilj version that does not resemble an item of sporting equipment. No modern instrumental temperatures are plotted so this is a comparison of the ‘shaft’ only.

His surmise about why his reconstruction differs from the Mann figure (some commenters have done an overlay and the differences are really not that remarkable, to my eyes) is beyond my ability to parse. To do so seems to rely on having read previous posts where terms are defined. Fair enough, but two points are clear – the two warm periods reconstructed – Medieval and late 1700s are >0.6C cooler than recent NH anomalies of around 1C CRU], which means that while the details differ, McIntyre’s plot is fully consistent with the conclusion of Mann et al 2008 that recent warmth is unprecedented for 1,000 years or more.

[end update]

Gavin’s inline response to Phil Clarke was the second mention that the Mann et al 2009 SI had admitted the “validation” failure of the no-dendro reconstruction prior to 1500:

[Response: It’s also worth spelling out some of McIntyre’s thimble hiding here. First off, after a 7 years you’d think that he would be aware that the reconstructions are done in a step-wise fashion – i.e. you use as much information as is available as far back as you can. Back to 1500 you use everything that goes back that far, back to 1400 a little less etc. So a proper no-dendro/no-Tijl reconstruction will not just be made with what is available in 1000AD. Second, given all of the bluster about validation statistics, he never seems to compute any. Since the no-dendro CPS version only validates until 1500 AD (Mann et al (2008) ), it is hardly likely that the no-dendro/no-Tijl CPS version will validate any further back, so criticising how bad the 1000 AD network is using CPS is hardly germane. Note too that while the EIV no-dendro version does validate to 1000 AD, the no-dendro/no-Tijl only works going back to 1500 AD (Mann et al, 2009, SI). So again, McIntyre is setting up a strawman, not performing any ‘due diligence’ and simply making stuff up – all in order to demonstrate some statistical prestidigitation to the adoring commenters. – gavin]

This time, the point wasn’t missed. A few minutes later,(529 July 31) Nicolas Nierenberg asked Gavin to confirm the surprising information that the no-dendro reconstruction did not validate prior to AD1500:

Gavin, So just to be clear with regard to your response to 525. Under either method (CPS or EIV) it is not possible to get a validated reconstruction to before 1500 without the use of tree rings, or the Tijlander sediments. I understand, of course, that as you remove proxies that the ability to project backward will naturally diminish.

[Response: That appears to be the case with the Mann et al 2008 network. Whether you can say more general things about medieval times using these and other proxies (cf osborn and briffa 2006) is another question. -gavin]

Read that again slowly:

Under either method (CPS or EIV) it is not possible to get a validated reconstruction to before 1500 without the use of tree rings, or the Tijlander sediments.

How many times had Gavin and others said that Mann’s use of Tiljander sediments didn’t “matter”? And now we learn that, without the contaminated sediments, 800 years of “validation” are eliminated. Gavin petulantly tried to close off the issue by saying said that “the exact level of the medieval warmth is not a very interesting scientific question”, not the position that was taken in September 2008 when they were issuing press releases about the no-dendro reconstruction.

Mann et al 2009 (Science) was published in November 2009, just before Climategate, and hasn’t been discussed here. In a way, I’d sort of presumed (prematurely, it seems) that people had stopped taking this sort of article in Science (or Nature) seriously.

There was nothing in the text of Mann et al 2009 that stated or even hinted that claims in Mann et al 2008 on the validation of their non-dendro reconstruction were conceded to be no longer valid. Nor did they issue a Corrigendum for Mann et al 2008 at PNAS where the no-dendro claim had actually been made. Nor was the withdrawal of the claim to have a 1300-year validated no-dendro reconstruction reported at the Mann et al 2008 website. Nor were there any press releases withdrawing the claim of a “validated” no-dendro reconstruction with equal prominence to the original press release. However buried in the SI to Mann et al2009 at Mann’s website was the following admission (with a similar caption to their SI Figure S8):

In addition to the tests described by ref. S1 which removed alternatively (a) all tree-ring data or (b) 7 additional long-term proxy records associated with greater uncertainties or potential documented biases (showing the temperature reconstruction was robust to removal of either of these datasets), we here removed both data sets simultaneously from the predictor network (Fig. S8). This additional test reveals that with the resulting extremely sparse proxy network in earlier centuries, a skillful reconstruction is no longer possible prior to AD 1500. Nonetheless, even in this case, the resulting (unskillful) early reconstruction remains almost entirely within the estimated error bounds of the original reconstruction.

Ironically, attention to the no-dendro reconstruction was revived because of attacks by Tamino and Gavin Schmidt on Andrew Montford’s summary of the original CA discussion of Mann et al 2008 and the Tiljander sediments, a summary that is worth re-reading in light of recent admissions:

It turned out that the twentieth century uptick in Tiljander’s proxies was caused by artificial disturbance of the sediment caused by ditch digging rather than anything climatic. Mann had acknowledged this fact, but then, extraordinarily, rather than reject the series, he had purported to demonstrate that the disturbance didn’t matter. The way he had done this was to perform a sensitivity analysis, showing that you still got a hockey stick without the Tiljander proxies.

Great care is needed when reading scientific papers, particularly in the field of paleoclimate, and this was one of the occasions when one could have come away with an entirely wrong impression if the closest attention had not been paid. The big selling point of Mann’s new paper was that you could get a hockey stick shape without tree rings. However, this claim turned out to rest on a circular argument. Mann had shown that the Tiljander proxies were valid by removing them from the database and showing that you still got a hockey stick. However, when he did this test, the hockey stick shape of the final reconstruction came from the bristlecones. Then he argued that he could remove the tree ring proxies (including the bristlecones) and still get a hockey stick – and of course he could, because in this case the hockey stick shape came from the Tiljander proxies. His arguments therefore rested on having two sets of flawed proxies in the database, but only removing one at a time. He could then argue that he still got a hockey stick either way.

439 Comments

This is the appropriate place for Amac to discuss Tjilander and have litmus tests of “Mann defenders”. Please keep a muzzle on him from bringing it up in every single other thread as that is offtopic. 🙂

The only issue in respect to the Tiljander sediments is the obtuseness of the “community”. It’s an obtuseness that unfortunately subtracts from their credibility. In this as in other such problems, they would be better off just conceding the point, making the relevant corrections and disclosing them plainly. It’s not as hard as it seems.

Although the issues and details differ so much, it may be worthwhile making a comparison of the failings of the climate science “community” to recognize such data analysis problems with the now prominent recognition of some notable failures in medical research.

Worth comparing how so much important medical research could (perhaps) suffer from confirmation biases and expectations of the “community” of reviewers with a lot that has happened to date in climate science with shaky data and methods. (see my next comment for link)

“Some researchers, reading the paper now, say they are as astonished as the researchers were when they saw the data.

“When I read the paper, I was stunned by just how bad the mouse data are,” Dr. Fink said. “It’s really amazing – no correlation at all. These data are so persuasive and so robust that I think funding agencies are going to take note.” Until now, he said, “to get funding, you had to propose experiments using the mouse model.”….”

From the NYT article, … it is very hard to kill a mouse with a bacterial infection. Mice need a million times more bacteria in their blood than what would kill a person.

Twenty five years ago I spoke with a researcher working on sepsis for a major US drug company. He told me that they couldn’t use rats or mice because they were so resistant. He used dogs which were much more expensive but also much more sensitive.

Sepsis research in the next millennium: concentrate on the software rather than the hardware.
” … We propose to focus research on the interactions between the constituents of the system rather than only describing isolated aspects of the disease process. We also conclude that the ideas and techniques of non-linear systems theory are suitable tools for the analysis of complex and dynamic diseases like SIRS and sepsis.”http://www.ncbi.nlm.nih.gov/pubmed/11795662

You put a lot of work into the post and from a first skim, it seems like an explanation that is coherent. I will read through it and comment on the content. I’m not up to speed on this specific kerfuffle and need to read and think about it.

I don’t want to get tooooo much into your general impression of the team other than to say that there’s something to what you say, but perhaps not all that you make it out to be. And that I see some similar failings on your side as well.

But no more. Will spend some time really reading through your post and giving an itemized response.

P.s. Thanks for not deleting my little jest about rectangle ownership. It made me cheerful for some reason. 🙂

Your VoG comment was fair. In circumstances where I’m just debating, it’s better not to use it. It’s probably a better policy to lay off the VoG though sometimes it’s helpful in responding to something personal.

I’ve also been aware of this as a weakness of an otherwise cool system. In other words, I like the power of the VoG when I’m an almost intravenous reader of CA but when (like now) I have a few other things to do the fact that it doesn’t appear in ‘Recent Comments’ and doesn’t have a datetime stamp can be a downer.

scientist said:I don’t want to get tooooo much into your general impression of the team other than to say that there’s something to what you say, but perhaps not all that you make it out to be. And that I see some similar failings on your side as well.

I’ve read CA for several years now, and I understand the malady you suffer from. I had the same problem, at first. Now, understand that I haven’t been around here for a couple of months lately and so have only seen a couple of your posts, but from what I’ve read so far, you would do well with more reading and less posting. Get yourself up to speed. Read the North and Wegman reports, and the shenanigans that went on. There is a long history between Steve and the Team. I find it quite remarkable that Gavin is actually referring to Steve by his actual name! This is real progress.

The malady you suffer from? Naivete. 🙂 You believe the Team can’t possibly be at once so obtuse and yet so highly regarded. If you still aren’t convinced, just follow the discussion of whether the Team believes Tiljander is used upside down or not. That one episode speaks volumes.

“You believe the Team can’t possibly be at once so obtuse and yet so highly regarded.”

So true. Getting up to speed on the extent of the team’s sloppiness, pettiness and obstinate refusal to allow anyone to check their work is a spiraling process. Each time around you think “I can’t believe it was even worse than I thought” only to spiral around even lower. He will find that his estimation of their reputation can be modeled fairly well by a toilet.

Dan, well said and the same experience I have had. Science, real science, is easy to defend, easy to discuss, easy to share data on, easy to allow others to validate, etc.

What I’ve observed from the Team is the opposite of this. Completely.

scientist – don’t know if you are, but I am (PhD Chemical Engineering). I hope the smoke clears for you soon and what you’ll see is that the smoke is created by the Team and it shouldn’t have been there in the first place. It is there only because very valuable grants/funding are on the line and the best way to capture the lion’s share is to build a Team and exclude all others.

Peace to all and thanks to all who are fighting to clear the smoke. Your energy and commitment seem boundless.

She notes that her studies correlate with previous studies in the same region and, to quote:

“During the Roman period there was in AD 140-220 an 80-year-long period in the Lake Korttajärvi area when organic matter deposition and the sedimentation was similar to that during the Medieval Warm Period (MWP), interpreted as milder climate condition. After this period, a clear mineral matter – organic matter varve structure existed, until the beginning of the MWP.

The MWP, AD 980-1250, was an exceptional period. The MWP is characterized by thinly laminated varves rich in organic matter, almost lacking the mineral pulses (i.e. spring floods), indicating mild climatic conditions. This period was interrupted by a colder period from AD 1115- 1145, dominated by mineral-matter-rich varves. The sediment deposited during the MWP was highly organic and dark brownish in colour. Based on pollen and diatom studies (Kauppila 2002), the MWP was a two-stage event. AD 980-1100 was warm and dry, a cold spell (AD 1115-1145) interrupted the warm trend and the following period AD 1145-1220 was again warm and even drier than the first stage.”

It is not as though this could be easily missed, if you were unbiased and looking for her primary conclusions.

The way Team minds seem to work is that since they assume there is a climate hockey stick out in the real world, therefore, any data shaped like a hockey stick is good, no matter how absurd its generation. Dr. Mann seems an Inspector Clouseau for climate.

Casey Stengel once asked of his hapless 1962 Mets, “Can’t anybody here play this game?” Sure looks applicable to this bunch, too. They’d resemble the gang that couldn’t shoot straight, but that assumes they could figuratively extract a gun from a holster, load it and pull the trigger without mishap and I doubt that.

Is Judith Curry the only consensus scientist capable of actually taking notes and asking questions?

And Steve, does the merry-go-round they put you through get tiresome? It must make you dizzy.

Thanks again Steve, for sticking with this. I can see why you were stonewalled though, as there is so much money riding on the hockey stick illusion being maintained. IMO, the open admission of errors of this magnitude would rightly put university funding into question.

Classic – yup! At first I found it shocking that the most elementary rules of rational discourse are abandoned but when one Manns it out what should one expect? Sadly, the contortions of Academia, I suppose.

Steve:
Thanks for pulling this together and connecting more of the dots. I still feel that Gavin’s comment that “the exact level of the medieval warmth is not a very interesting scientific question” is a very odd statement – almost an epigraph on a tombstone?
The ht to Nicolas is truly deserved. He flushed out some of the key quotations.

ED:
As to why the stonewalling, IMHO hubris amongst scientists and other experts is sufficent to explain most of the odd and counterproductive behavior that has surrounded this tale. Other attributions simply do not have evidence to support them. However, the CRU emails give a bottomless pit of evidence for Hubris – not to mention the response on Tamino’s Review of Montford’s book.

Another thing that completely puzzles me is the fact that if one simply averages temperature proxies, as Craig Loehle has done, one sees that the MWP was likely warmer than present times, and the largest problem of the previous 1000 years has been the LIA.

Is there a Tamino/Schmidt rebuttal of this that I could be pointed to?

[Response: Loehle’s reconstruction has dozens of problems – some of which were outlined here. It has no information on relative temperatures between medieval and modern times. To have a simple average work, you need a relatively even spatial sampling, and relatively equal representation in each proxy for a particular area. You can’t for instance average the mean Chinese temperature over the whole country with a single point in India and get a representation of the average variability in Asia. These things are not trivially commensurate. -gavin]

Uhm, doesn’t the bristlecone series pretty much represent the entire US. And doesn’t the temp stats for the entire arctic rely on very few actual sensors?

I’d just like to note this was my question which Gavin responded to. I raised the same query about geographical sparsity in the Mannian reconstruction in my response to the response – but unfortunately this didn’t pass through the vagaries of real climate moderation (which is pretty typical).

Is there a way to raise this question formally with PNAS or elsewhere?

I suspect Mann’s problem is not making the correction. His challenge is how to do so without giving credit to Steve and without making his use of the word “bizarre” in his response to Steve look silly. The strategy to avoid this seems to have been 1) make a correction as quietly as possible; 2) deny the importance of the issue (no scientific interest before 1500); 3) (to come) claim there is no need to issue a formal corrigendum because of 1 and 2.

>Mann et al merely stated that our criticism of their use of the Tiljander proxies was “bizarre” and that their

I posted on this thread https://climateaudit.org/2009/10/14/upside-side-down-mann-and-the-peerreviewedliterature/
that the only reasonable way to read Mann’s reply to the PNAS comment is that he thinks there is no a priori physical understanding for Tiljander, and therefore either orientation is correct and no one-sided test was used. This does not fit with the code for Mann 2008, but it is the only way to make sense of calling the accusation of upside-down usage ‘bizarre.’

Is there any way they could have done this latest round of white-out innocently? Is there any mechanism anyone can identify where Mann would just put a correction up naked and not have an ulterior motive?

It is widely known that his work is highly dubious, no serious scientist is now going to take the risk of relying on his work. So, the only people you are trying to convince are the hangers on and eco-zealots. Nothing you say is going to change their minds, WORSE, the more you are preoccupied with what Mann has said, the more these people think he is important: which he is not!

…but I know from experience that such listings are incomplete. So, yes, weird as it might seem, Mann et al. 2008 is apparently taken seriously by the “climate science” community, or at least they pretend to do so.

A quick stab with google scholar for citations of Mann08 since 2009 gave 65 hits (not all citations, from what I can tell). Here’s one example from NOAA, January 2010 (the quote below is from the first paragraphs of the introduction):

In particular, some of these reconstructions have played a key
role in estimating the amplitude and rate of change of the global/hemispheric energy balance response to anthropogenic greenhouse emissions [cf. Jansen
et al., 2007; Mann et al., 2008]

Steve’s preoccupation is not with Mann, it is with the prevalence of erroneous impressions in the public record. Mann, the man, has nothing to do with Steve’s fervour at all. Mann is merely the source of the illusion.

I wish I could believe, as you do, that Mann has been popularly rumbled. Certainly he has been, by Steve, and as an example I don’t think Judith Curry would use a CRU gridded set today (without making clear the uncertainties in the source data). But many other climate scientists believe that without a perfectly honed, straight handle on the hockey stick the value of their research would crumble to dust. And with it, their funding. Some may well be correct, perhaps even many of them.

But if we cannot have science with integrity, what have we got left? Thus Steve continues to strive for what is right and true, rather than what suits the advocates.

Gavin’s reply:
“the exact level of the medieval warmth is not a very interesting scientific question (given the uncertainties in forcings) – despite what you might read elsewhere”

By elsewhere I presume he means the last couple of IPCC reports. It beggars belief that he can say this after the enormous investment the climate science community has invested in convincing us that current warming is unprecedented. This is, after all, just about the only evidence produced that the current warming exceeds recent natural variation

Is he saying it is no longer of interest whether the current warming is at all unusual?

(I would love to ask him this at RC, but have learnt the futility of that approach long ago)

As a matter of fact it has been unusually wet in Sahel and Sahara this year because of a strong monsoon. Actually this is exactly what one would expect under a warming climate to judge from the past. However since most GCM predict drought in the Sahel/Sahara/Mediterranean and this is now an established part of AGW orthodoxy, this climate oddity has hardly been mentioned anywhere. Here is a map of rain during the last week in Africa:

he way Team minds seem to work is that since they assume there is a climate hockey stick out in the real world, therefore, any data shaped like a hockey stick is good

That seems to be precisely the assumption they operate under. I sometimes get the impression from their comments that they can’t believe they’re having so much trouble finding the hockey stick that simply has to be there. From memory Montford picked up on this exact point in his wonderful book somewhere – he found examples of data being abandoned because it “couldn’t be right” which was to say it was not hockey stick shaped.

(c) the net effect of the contamination following an uncontaminated record (which is then inverted), is the formation of a strong clear Hockey Stick, with uptick just at the correct point – pure chance but just what Mann wanted.

And this is also an admission that the weighting of these invalid proxies occurs out of all proportion. If ONE proxy is all that’s needed to make all the others produce a hockey stick, then something is seriously wrong with the method. Even I can figure that out.

Steve: I would urge readers not to try to re-state the issue into something that you presume, but do not know. What is on the table here is that the Tiljander proxies change the “validation” statistics for the reconstructions. I presume that the HS-ness of the EIV reconstruction for the early stages changes, but that’s a different issue that we haven’t examined yet. Also, as I mentioned earlier, the key issues with Mann et al 2008 is probably not over-weighting of individual proxies, but the impact of 6-sigma proxies and ex post screening of noisy data.

Steve, is it possible to use contaminated data to validate something? Wouldn’t the validating data have to be at least as clean and consistent as the validated data? I understand that the more validating series the better, but if I have data that I know is bad, haven’t I just given a false confidence to the validated data?

In my reconstruction without treerings, I originally misconstrued dates in 2 out of 18 proxies by 50 yrs (out of 2000 yrs)–this caused no end of scorn from Gavin. I issued a full corrected analysis. But when Mann uses proxies upside down…crickets. There is this word called “integrity”. They should look it up.

A couple of comments. While it seems entirely proper for critics to exhaustively find all flaws, it still baffles me that proponents can as actively work so hard in attempt to exonerate some findings that so tenuously uphold a specific hypothesis……so anti-science it would seem.

And too, if their desired ‘finding’ rests on a single (apparently) flawed proxy….then consider just how lucky (for lack of a Better term) us denialists were that the original author(s) were skeptical enough to actually note some of the problems ( ie recent modern contamination) with their series! One fears that the future might spawn climate researchers that are more focused on reviving their desired outcomes than in conducting true science. While this view represents the height of cynasism, one can’t help but accept at least a certain few are dedicated to such ‘findings’.

I share this concern. However, I think that if peer review actually means what the public imagines it to, then a lot of these problems would vanish. I found it very interesting that, according to a recounting of one of Steve’s discussions with Schneider…

“Schneider replied that he had been editor of Climatic Change for 28 years and, during that time, nobody had ever requested supporting data, let alone source code…He observed that he would not be able to get reviewers if they were required to examine supporting data and source code.”

If reviewers weren’t reviewing supporting data or code, what exactly were they doing? Spell checking? And if requiring reviewers to actually check data and codes would be too much effort for them to bother with doing it…well, let’s just say that I have a whole lot less faith in peer review than I used to.

However, I think that if peer review actually means what the public imagines it to, then a lot of these problems would vanish.[…]

[…]well, let’s just say that I have a whole lot less faith in peer review than I used to.

In this regard, it’s interesting to note the “silver lining” in the dark cloud known as the Muir Russell report, i.e. “Appendix 5: Peer Review”, authored by Richard Horton, editor of The Lancet. Horton observes:

[p. 127]:
“Much of the concern – and, indeed, confusion – about what took place at the CRU in relation to peer review may stem from misunderstandings about what peer review is and what it can be expected to do.”

[p. 131]:
“Everyone – scientists, the public, policymakers, politicians – would like to believe that peer review is a firewall between truth and error (or dishonesty) (15). But as the editor of one leading specialist medical journal has rightly pointed out,–There is no question that, when it comes to peer review, the reviewers themselves are the weakest (or strongest) links”

[p. 132]:
“Unfortunately, there is evidence of a lack of evidence for peer review‘s efficacy”

In an article for the Guardian (circa release of Muir Russell review) Horton also notes:

“[S]cientists need to take peer review off its pedestal.
[…]
“If we treat peer review as a sacred academic cow, we will continue to let the public down again and again.”

Medical Peer review while sometimes lacking does at least look at the data and look to see if the appropriate statistical test were used. Limitations of the study and applicability are almost always spelled out.

Most of the problems with pharmaceutical literature is that study results are applied to drugs and patient populations that were not studied. “Class effects” Because Drug A in family B does Y in Patient Population X then Drug B in Family B must also do Y in Patient Population Z….

Also even “Land Mark” trials can be hottly debated in letters to the editor. Look at the current JUPITER controversy on the pages of the major medical Journals. This post publication “true Peer” review seems to be missing in Climate Science.

Please remember peer reviewers are unpaid volunteers. It is unrealistic to expect people with existing full-time jobs to take out week (or even 2-3 days) to review a single paper.

It most fields this problem is minimized by:

1. Having publications that are not based on mountains of supporting data and complicated code.

2. Having fields that contain intense competition, where proving someone wrong is rewarded with prestigious publications. The Climate field seems unique in this regard in that there seems to be a powerful clique of collaborators that dominate the field.

I have made an effort to record literature citations and blog posts that discuss the use of the Lake Korttajarvi (Tiljander) lakebed sediment records in Mann08 (PNAS). The compilations may be useful to newcomers to this story.

Mann08 considered four measures that Tiljander and her co-workers derived from their lakebed sediment drill cores. Thus, there are four Tiljander proxies. Two of them are miscalibrated and “upside-down,” one is miscalibrated and rightside-up, and one is miscalibrated and of indeterminate orientation. Thus, miscalibration rather than upside-downedness is the core (heh) issue.

For an exhibit of the best current AGW Consensus arguments in favor of Mann08’s uses of the Tiljander proxies, see the (ongoing) comment thread of Arthur Smith’s post, Michael Mann’s Errors (while a supporter of the AGW Consensus, Arthur has done a commendable job as an ‘honest broker,’ allowing all parties to have their say.)

Within that thread, my comment “It’s certainly helpful to…” describes the three proxies’ assignments in Tiljander03, and contrasts them with the assignments for them in Mann08. (A climate-related discussion of the fourth Tiljander proxy, “Thickness,” was not provided in Tiljander03. Thus, Mann08’s use of it cannot be “upside-down” or “rightside-up” with respect to the earlier authority’s interpretation.)

In the body of his post, Steve mentions my recent involvement in L’Affaire Tiljander. While his characterizations of my interior state (e.g. “frustrated”) are inferences, they are correct.

Mann’s paper’s central claim was a 1300 year tree-less reconstruction skillfull enough to make “recent warmths appear anomalous”.
But Mann’s corrigendum says the above reconstruction is NOT skillfull. Worse, it says it’s skillfull only thanks to the misused Tiljander’s series!
So wouldn’t the logic outcome be the retraction of the paper, not only because the central claim is false but also because the “skillfullness” criteria used by Mann are useless and even misleading?

Except for the bolded portion of Gavin’s “response,” I find his comment confusing. After six years of trashing you as an incompetent auditor, incapable of understanding the nuances of Mannian reconstructions, he now appears to be trashing you (in front of your “adoring” audience) for NOT exercising your competentence(?) and realizing, independently, that Mann 2008 didn’t do what Mann and Gavin, and their adoring audience, said it did. All of which is a bit rich.

Consistency, for Gavin, I guess, is indeed the hobgoblin of little minds.

Submitted to position #552 in the RealClimate.org moderation queue for The Montford Delusion, 2 August 2010 @ 9:54 AM EDT —

In Comment #551 supra, Phil Clarke notes that Steve McIntyre has posted a new discussion of the Tiljander proxies’ uses in Mann08 (PNAS) and Mann09 (Science). His remarks rely on some of Gavin Schmidt’s in-line Responses to comments in this thread, and thus may be of interest to some readers.

Can Steve McIntyre respond to this post at your page? If yes, then I am going to believe that this is really about the science. Audiatur et altera pars

and the Latin means “The other side should be heard”

To me, it’s dhogaza’s rather typical reply to the above, that is like what Mosh has understood. I think this post is another very interesting hairline crack. Though of course it’s up to Steve what he wants to make of it.

Must be a slow news day. I notice also that he seems to conflate the 7 potentially problematic datasets – which encompasses Tiljander, Benson, Isdale and McCulloch – and places all the ‘blame’ for the reduced skill before 1500AD on Tiljander alone. Sloppy.

As a skeptic, one of my personal tenants is to not assume my first instinct / impression / conclusion is right. I’m always willing to be convinced that I’m wrong. This includes my long doubts about some of the science that is on display concerning global warming. I visit RC from time to time, hoping that I’ll find some conclusive reasoning that will show that they are indeed right. They are supposed to be the guys in the know after all. The I come here, and I find stuff like this:

—————————————————

At realclimate:

Must be a slow news day. I notice also that he seems to conflate the 7 potentially problematic datasets – which encompasses Tiljander, Benson, Isdale and McCulloch – and places all the ‘blame’ for the reduced skill before 1500AD on Tiljander alone. Sloppy.

Uh, Benson, Isdale and McCulloch all start after 1500.

—————————————

Upsidedown Tiljander was not supposed to matter. Those reconstructions were “robust” and “skillful”. How DARE YOU try and accuse the highly esteemed and brilliant MANN of using a proxy incorrectly. You stupid deniers are flat out wrong! Now even Gavin admits that it does matter, and Tiljander does screw the 2008 study up. Yet Mann get a pass on having to take heat for the error.

And then there is your “Mann Bites Dog” post, to which I’ve not seen a reply at RC explaining the confusion on Tamino’s part.

Sorry, but every time I try to be convinced that I’m wrong, and the science is as “robust” as they claim, I alway end up disappointed.

one wonders why the topic even deserves a chapter in the IPCC, something that folks like McIntyre has argued. One wonders why debates over simple mistakes (such as typos on lat/lons) are so vigorously defended. One wonders why something so un interesting scientifically appears to take such an iconic role in public presentations.

In his mail to Dr. Mann, a mail that had as its subject “Subject: IPCC & FOI” Dr. Jones asked Dr. Mann to delete emails related to Chapter 6, the chapter on reconstructions. .Mails that would have related to the scientifically uninteresting topic of the levels of warming in the MWP and specific arcane uninteresting statistical questions about uninteresting papers:minutia. To be sure, both scientists have been cleared on any wrong doing in this exchange. But that was never the issue. The issue, in my mind, was ‘why this fuss over something that does doesnt matter.” It’s singularly odd that Jones would fight to prevent the release of uninteresting mails about an uninteresting topic. Even more odd that he would risk asking people to delete mails about this scientifically uninteresting topic. It’s singularly odd that people would resist sharing code and data about this uninteresting topic. It’s interesting that people would continue to fund this uninteresting topic.

If they are smart they will argue that what gavin was talking about was the EXACT level of warming. And they will say THIS is uninteresting. But the GENERAL level of warming ( the big old uncertainty region) Exceeds the current warming and THAT is scientifically interesting.

Which would return the discussion to the uncertainties. And thus to the question of why they wanted to limit the uncertainty. Skeptics sell doubt! Ch06 needed to sell a different product.
Overpeck made that clear to Briffa. Tough marketing job for Briffa How to sell doubt as relative certainty.

The re-defining of the MWP is also a part of “it doesn’t matter.” Because soon, the MWP will have been re-defined to be a very local and minor departure from the long-term Global averages. The re-defining is underway at this time.

just thinking of running some sensitivities on Mann’s studies.
using regem to infill a temperature series that has only 10% of the data there seems a bit far fetched. also the weird description of the global series being the average of the NH and the SH.. does that mean area weighted average?

nits I think, but just curious. given mann’s tendency for making geographic errors that would be the first place I would check his code.

Phil Clarke’s last RC comment mentions this thread while failing to quote a single word of Steve’s. It seems that despite his non-quote, there is a flurry of interest eg Deep Climate’s own thread, linked at RC#532, one post after Nierenberg’s post that drew the double response from Gavin.

From Deep Climate I found the link to Mann’s website, the SI notes for Mann 2008, in which there is a note about his new (Nov 2009) graph comparing recons with/out “the Seven” and/or BCP.

UPDATE 4 November 2009: Another error was found in the corrected Supplementary figure S8a from December 2008: The previously posted version of the figure had an error due to incorrect application of the procedure described in the paper for updating the network in each century increment. In the newly corrected figure, we have added the result for NH CPS without both tree-rings *and* the 7 potential “problem series.” Each of the various alternative versions where these sub-networks of proxy data have been excluded fall almost entirely within the uncertainties of the full reconstruction for at least the past 1100 years, while larger discrepancies are observed further back for the reconstruction without either tree-ring data or the 7 series in question, owing to the extreme sparseness of the resulting sub-network.
The new figure can be downloaded here (PDF)

Note his exact words. I now understand that “the Seven” includes Tiljander, and other records Mann found to be “potential problem series”.

So the key line in the graph is the turquoise line, which is also the one that has been most visually buried, most particularly by the instrumental record overlay. I’m sorry if I’m daft, but it seems that real calibration should make the turquoise proxy line fit exactly behind the red instrumental line, not tailing off at the (?)”hide the decline” mark. Or perhaps calibration for recent decades is not possible because the thermometer record itself is under suspicion. But if it was made to fit, it looks like the turquoise MWP squiggles should be even higher and clearly higher than the CWP.

But to be sure, I’d need to reassemble the graph myself, and I don’t have that skill.

Thanks for reminding me where I had heard that Mann had successfully created a long-term reconstruction without the use of tree rings. This for me took care of the various issues that had been discussed on those series. I thought that was quite an important claim. I knew there was an issue with Tijlander, but I was unaware until I saw Gavin’s comment that dropping Tijlander invalidated that claim.

I followed up to Gavin’s post on real climate but it didn’t get through. I thought it strange that he said that medieval temperatures weren’t interesting, given this is what paleo guys do. I suspect what he means is that it shouldn’t make any difference in decisions about energy policy, which is where I feel that a lot of these discussions break down. Real climate wants to stay absolutely on message without the slightest admission of error or important uncertainty. They do this to have the maximum influence, in their minds, on policy. But in my opinion this winds up having less impact than if they would let the chips fall where they may in which case they would be much more influential on someone like me.

Gavin’s reply:
“the exact level of the medieval warmth is not a very interesting scientific question (given the uncertainties in forcings) – despite what you might read elsewhere”

I’m dumbstruck.

If the central question is whether the current warming is statistically significant, then one must know something rather precise about the past to answer this question. What, pray tell, does Gavin think would be an “interesting scientific question” as it relates to Paleo-climatic reconstructions? I honestly can’t think of any other question that could be more important.

mpaul:
Pondering Gavin’s quote further – he says becuase we don’t understand the forcings during the MWP it is, therefore, scientifically uninteresting. Isn’t this also largely true of the LIA? His explanation of this little gem is going to be interesting.

Nicolas suggests that Gavin is noting that whatever the actual forcings they have few implications for future energy policy. It is possible, but I doubt it. Gavin is a very smart guy. The Ptolemeic complications needed to support Mann’s reconstructions are undoubtedly visible to him.

Bernie,
To my simple mind, the MWP can be looked at in a couple of different ways. Gavin might be right if he means that because we don’t know the forcings, if any, which produced it, it has no pertinence to now.

But the pertinence would be that we survived it and there was no climate run-away – but again, unknown forcings and unknown feedback environment. At least it seems doubtful that it could have been anthropogenic in any significant way.

It also demonstrates that nature can make it warmer without any help from us.

So it comes down to 1. are we doing it to ourselves? 2. are we helping nature? or 3. is nature once more doing it to us?

It may be that the mechanism for what’s happening now, if it is happening, is what’s unprecedented, not the magnitude.

And if this is what the issue is, it seems unlikely that there is anything to be gained by continued investment in paleoclimatology.

We already know we can soldier on through a warm period of the MWP variety so maybe that’s the only lesson there – as Gavin says, not that interesting.

Gosh. It looks like someone would actually have to get into hard science – no more teleconnections and similar nonsense – hard science.

J Ferguson:
I just read the Mann Science Article (Nov 27, 2009). Mann et al (sans Gavin) certainly appear to see the cause and magnitude of the Medieval Climate Anomaly (cute rebrand) as meriting an article in Science. Mann et al certainly seem to suggest that a repetition of the natural forcings that produced the MCA coupled with CO2 induced warming could land us in a heap of trouble.

However, I can’t quite figue out how La Nina and El Nino event are linked to essentially 300 year time periods. Nor do I see, given the paucity of SH proxies, the basis for the assertion that “The Medieval period is found to display warmth that matches or exceeds that of the past decade in some regions, but which falls well below recent levels globally.”

Yes, in context, I think you are properly capturing Gavin’s thoughts. Or said another way, “we don’t know what caused it, so its not worth worrying about, except to say that whatever forcing existed back then don’t exists today, even though we don’t know what they were, except to say that whatever they were they are not interesting because we know it wasn’t CO2 and since we know that CO2 must be the problem, anything that doesn’t point that way is uninteresting, scientifically, that is”.

mpaul:
I think Mann et al deserve more credit than that. The Science article (Nov 27, 2009) does pose alternative forcings, which if they reappeared might lead to an amplification of whatever existing warming there is. As I noted elsewhere, the discussion seems hugely speculative but it is inherently scientifically interesting – based on the article being accepted by Science.

Gavin is a spokesperson for an advocacy blog so his spin, although misleading, is rather expected. Mann as a scientist/advocate has a much harder task and thus makes admissions of previous over-statements in the caverns of an SI.

I think we learn from all this that you read, re-read and read again some of these climate science papers and carefully note what was not stated and by all means go over the SIs with a fine tooth comb. We also learn that RC remains RC and presents the evidence for their case and attempts to minimizes the damage of valid criticism.

Also learned is that there are those with the audacity to come on here with a blog name of Scientist and criticize everything here but the science content of this blog (as in “I am not yet up to speed”).

Learned finally, is the impact of a well-constructed and reasonable sensitivity test, i.e. the ones without the pea under the thimbles.

Finally though a word of caution, that despite these revelations presented here and elsewhere, the scientist/advocacy approach to publishing a paper, making the claims and having those claims embraced by the media and then “moving on” without any repercussion in the MSM for any rushes to judgments that might be revealed later, the approach appears to be working – for advocacy not science.

I’m just saying that reading the post and even the Mann paper is not sufficient to opine on the issue here. If you’re fair, you go to the next step and consider how your own side might be wrong.

My posts might be a little draggy compared to some that have hashed this thing over for a while, is it really that, that bugs you, or that I’m not enough on your “side”? And if things were so open/shut simple, it would not be nescessary to have so much background, no?

I don’t seem to see any objection to gestures posts like PGossilin “How long will Science and Nature keep enduring this? Mann has got to be a growing liability.” Would you prefer more of those style posts, and less attempts to come to grip with the issues of the headpost?

AMac challenged me in another thread (on this issue), I spent time and am attempting to do him the courtesy of responding. Do you want more ingroup cheerleading or to be pushed a bit? I love being pushed…it’s like heavy squat exercises for the brain muscles.

Following AMac and Steven Mosher’s lead, I have just posted the following in the RC discussion (awaiting moderation at 6:03 pm). (Feel free to correct any misstatements … I’m not as good at this as S. McIntyre, even though I stole liberally from his points.):

Gavin said: “…but showing that [the no-dendro/no-Tilj 1000 AD network] is problematic while implying that someone has made some claim about it that that [sic] you are refuting is a classic strawman argument.”

And also: “…the ‘issues’ raised have no actual consequences … McIntyre and Montford then repeat the same issues and same points, and complain when the scientific conclusions don’t change even when its been shown that those issues and points are not material.”

One of the central claims of (Mann, 2008) – as stated in the abstract – was that “Recent warmth appears anomalous for at least the past 1,300 years whether or not tree-ring data are used.”

Now Gavin has confirmed, by citing the Mann 2009 SI, that the no-dendro/no-Tilj reconstruction cannot be validated earlier than 1500 AD. He further stipulates that no one has been claiming otherwise, and to say so is a “strawman” argument. But Mann had this to say regarding the Tiljander series:

“Potential nonclimatic influences on the Tiljander and other proxies were discussed in the SI, which showed that none of our central conclusions relied on their use.”

It seems impossible to me that excluding the Tiljander series has “no actual consequences” if doing so reduces the skillful length of the no-dendro reconstruction from 1300 years to 500 years. Further, since the 1300 year length of the no-dendro series was one of the central claims of the paper, and since Mann later stated that removing the Tiljander series made no difference, then it is not a strawman argument to repeat, and then rebut, this claim.

Gavin also makes the extraordinary statement that “…the exact level of the medieval warmth is not a very interesting scientific question.” Really? That would seem to be at odds with past posts on RC, on Mann’s take on the importance of Mann, et al., 2008 (not to mention MBH98), and in fact on the whole field of paleo-climatology. A significant MWP would undermine the idea that current temperatures are unusual (and therefore man-made). It seems to me that a modest, lower-than-present MWP has been claimed many times in recent years, and that those claims – when examined – have not held up to scrutiny. Thus, the demonstrated lack of skill before 1500 AD in the no-dendro/no-Tilj network is quite significant. I personally find this to be very interesting.

Gavin,
” Of course if you remove all data that is imperfect, you will end up with no results.”
And that is exactly what should be done!
The problem with all proxies is they can be consciously or unconsciously manipulated, especially when the data is random numbers to begin with.

Because the number of non-excluded proxies is being reduced, it might be an optimum time to look at a critical part of the remaining proxies. I’d be very keen to see a series of graphs/tables relating proxy response property to temperature, that is, the core calibration step. It’s far too much to ask Steve to divert onto this. My excuse is that I have severe family health complications and I am a bit removed from the key publications in any case.

If a couple of specialist CA writers can cut and paste the calibration graphs, I’m sure that many of us would be helped by gaining an appreciation of goodness of fit, assumptions, caveats, etc. I think many of us need this because the discussion has become so detailed that a quick step-back overview would be most helpful.

The key issue is one of sensitivity testing to the exclusion of questionable proxies. If you think a proxy is absolutely VERBOTEN BAD, then you shouldn’t use it no matter what. And the sensitivity test is irrelevent, because you just exclude. If you think a proxy is questionable, (maybe has some hair on it, but maybe has some info, maybe has people with different opinions of it’s usefullness) then you run the sensitivity test. If the answer is qualitatively inaffected by exclusion, then the issue becomes moot. It the answer DOES change, then you basically know that your state of knowledge is “if-then”. (e.g. if I beleive the market survey report, THEN the target acquisition is a worthwhile investment.) It just illustrates a dependency.

For instance, Mann is upfront that prior to 1300 years, regardless of method, that tree-rings are required to get an answer. IOW, there is a dependancy. Another dependancy is on methodology, if you beleive CPS is the way to do things, then you don’t have a tree-less answer back to 1300. IOW, there is a dependancy on methodology choice. (He does make an argument for why he thinks EIV functions better than CPS, but again…there’s a dependancy…if you beleive those qualitiative arguments, fine, you’re set. if not, there is an issue.)

The key question to me is what sort of “questionable” is Tjilander? Is it a complete mess, that all sides agree should NEVER be used, no way no-how? Or is it sorta more like the tree-rings, which mayb have utility, but are in question.

If they ARE like the tree-rings, then I think the pea-thimble stuff is actually valid. You just have to realize that the recon is sensitive to exclusion of two questionable species, but not one. That means…well you’r dependent. As long as one or both ar valid, you’re ok. In the event both assumptions are off, you’re not. (An M&A analogy might be that as long as EITHER the market research study OR the expected war driving demand for widgets are valid, your NPV will be sufficient.) Of course, intutively, the more restrictions you put on something, the harder it is to pass a test.

I’m really intrgued what the opinion of Mann et al are on the Tjilander series themselves. Leaving ASIDE sensitivity, just looking at the proxy, do they see it as hopelessly compromised, gold standard good, tcpical amount of hair, or seriously questionable but may have info.

I’d also like to see the Tjilander paper (haven’t read that yet, time limits).

In the past, I have NOT been impressed by Mr. McIntyre’s logic or fairness on questioning the bcps. He references an NAS panel that winged it, rather than a “stake in the heart” science review full of statistics and physics and chemistry. The bcps might have some hair on them, but they are at least a plausible proxy. Not like…I donno…dotcom stocks or fraudulently created series from scratch (ala Piltdown man).

Also note, that the comments of ths study collectors are…useful…in thinking about how to use their data…but don’t rule out other interpretations. After all, Michelson never beleived in relativity, evne though his data helped found the theory. NOte: I’m not saying that I think Tjilander is a “good” proxy. Or even that it’s in the middle “qeustionable ground”. But just describing how I think about this, based on a limited amount of looking and what I would want to see next to know more. and a bit of context on my level of proof and lack of bias (not appreciating theprevious CA “hopeful” interpretaitons of bcps as being cause by opportunistic different non-climate causes: dry lakebed blowing, sheepgrazing, CO2, precip, missampled (Ababneh), damaged bark. IOW any port in a storm, anything that helps our side…and makes bcps “not a proxy”…since well they are so darn hockey stick creating…gotta get rid of them.)

So if Mann (or you) see Tjilander as equivalent to bcps, I think you are being a little unfair to him. If Tjilander stuff is WELL WORSE than bcps and just something to never, ever use…then Mann would not be answering criticism properly to do the pea-thimble, one at a time sensitivity. Instead of evaluating sensitivity first, the key thing for him is to say are the sediments absolutley awful or just kind of like bcps and have some hair on them. If absolutley awful, then of course, he should pull them and then it does affect his ability to do tree-less recons (after losing the Finn sediments).

*based on reading the paper and a sampling of the blogposts. Over an hour of time, under a day. (btw: was turned off by the phrenology post, how it started. Not going to spend time on stuff like that…will wait for someone else to write stuff up sans snark (as seemed to be done here, so worth my waiting!))

One reason I’m curios to see the Finnish paper is I wonder exactly what they say about their samples (in terms of contamination) and how can they argue the sign is different (or calibrate at all) if the recent data was messed up by land use. Is their some physical argument? Calibration using undistrubed areas?

The fundamental problem with Mann08’s use of the four Tiljander proxies is this:

1. Mann08’s methods absolutely require that proxies be calibrated to a gridcell derivation of the instrumental temperature record, 1850-1995.

2. The Tiljander proxies cannot be properly calibrated to the instrumental temperature record, because non-climate local factors progressively overwhelm any climate-related signals, in the 19th and 20th centuries.

3. Mann08’s authors mistakenly set aside the Tiljander03 authors’ warnings of contamination, and performed a set of four faux calibrations. 1850-1995, the major influences on the varve series were nearby agricultural activities, roadbuilding and bridge reconstruction, and lake eutrophication. These activities caused Darksum, Lightsum, X-Ray Density, and Thickness to increase during the screening and validation periods. The gridcell temperature anomaly calculated by CRUTEM3v also increased during those periods, leading to positive correlations between proxy values and temperature. The correlations of Darksum, Lightsum, and Thickness were judged sufficiently high to be Significant (XRD’s correlation was lower).

All four correlations are meaningless in that they have nothing to do with any causal relationship between any climate-related factor and any proxy-related characteristic. A trivial consequence of this procedure is that Mann08’s authors unwittingly assigned meanings to Lightsum and XRD that were opposite in orientation to the assignments proposed by the only relevant authorities, Mia Tiljander and the co-authors of her Boreas paper in 2003.

So that this comment passes moderation, I will provide links to references separately. Or you can Google “AMac Tiljander” and find them yourself.

While, I haven’t followed the intricacies, I DO understand that there is a concern that the lakebeds were upset by construction and that this could render the series physically meaningless and that while calibrations could be done, they might be off because of the contamination (points 2 and 3). No need to repeat that “concept”. I want to go to the next level, not repeat the first level. Want an understand of the nature of the concern. How serious it is, level of agreement by the parties, etc.

P.s. I’m not sure it’s relevant to your point, but I think you’re wrong about point 1. See the first paragraph on 13253 (EIV method).

P.s.s. An issue that could cut either way: I wonder why they are able to calibrate the sediments (pass a test or whatever) given the bridge-building? Does that imply the bridges didn’t disturb the mud or that anything can pass? (doubt that, since some series failed, no?)

My purpose was to explain my thought process and to be fair. Not to ask rhetorical questions. I agree that is a natural next step although perhaps not the first. Would say looking at Tjilander paper comes first. 😉

All proxies must start with biochemical hypothesis for the relationship between the proxies and temperature (i.e. tree rings increase in width as temperatures increase). The Tjilander paper conclusions about contamination are likely based on this hypothesis. However, one cannot rule out the possibility that their biochemical hypothesis is wrong and contamination is not sufficient to explain the divergance. But that would simply mean the Tjilander proxies are pure junk should not be used.

You appear to find your display of venture-capital-related acronyms to be rakishly insouciant. Further, you’ve graced the Climate Audit readership with a detailed description of your lack of due diligence on the subject at hand. This, while the requisite blog posts and literature PDFs are an easy click away (e.g.).

no doubt, like arthur, he will find himself too busy to consider the matter or will weasel a way out of a direct comment. If he finds some fault that fault will be minimized by some fault of your’s or mine or Steve’s or the dogs. And why are you worried about a 2 year old paper, science is self correcting and besides reconstructions dont matter, move along

If you skeptics did this more amonst yourselvs and against Mr. McIntyre, you would sharpen your cases.

Sigh! What makes you think we don’t? You don’t have to read all that many of Steve’s head posts to notice how often he incorporates corrections made by posters here. In the early days, sometimes when a thread was new, he’d just make the change and go from there but then he got dinged for failing to credit the correction so now he always leaves the correction in the thread and adds a note like “changed”. If it’s a major change he’ll add an “update”. OTOH, Steve does know more about the statistics of tree-ring proxies than just about anyone, so it’s difficult to find much wrong when he’s in his area of expertise. You’ll note the Team won’t engage him directly. They snipe from as far away as they can get.

BTW, you might want to go to Roy Spencer’s site and look at the threads where he tries, with not much success I’m sorry to say, to get some of the untrained skeptics to admit that the sky is falling… I mean that a hotter object can be warmed by a colder object via back-radiation.

Excuse me. You havent followed me. I’ve long argued for a ‘murder board’ type of review for everything. That’s my training. Submit your work to your critics.
Give them the code and the data. If your argument doesnt survive your harshest critic, tough luck. more proof is required.

I am not a skeptic. I believe in AGW, just ask around.
I don’t believe in sloppy science.
I dont believe in poor practice when it come to acknowledging errors.

1. They’re not a “click away”. The headpost did not even give a citation for which Mann article. I found it from RC, though. I glanced over your post (which came after the headpost, btw) and did not see a citation for the Tjilander paper. Please supply. That’s not in the OP, either.

2. Maybe this is dreary, but it’s the only way to be fair. You can’t simultaneously say “this is simple, if you don’t get it, you’re covering for the team” and then “but you should have read 10 different blog posts and 2000 different comments within comment threads”.

3. How about engaging on the content. Did you understand my point about proxies that are questionable (as for example tree rings themselves) versus proxies that are 100% unsuitable?

I think I can answer your third point only from what I’ve read here; if I’ve gotten something wrong, someone else will correct me.

The short answer is yes, “anything can pass”, as long as the data is going in the same general direction as the temperature trend, which is up. In some of the cases, the theorized relationship between the sediments and temperature was actually reversed by the modern contamination. The modern trend, in the reserve direction, was found to have passed verification as compared to modern temps, even though this is obviously completely spurious.

Regardless, if someone is supplied data with the caveat “this data should not be used in these ranges because it is unreliable”, and there is no way to qualify or quantify exactly how this unreliability will manifest itself, the only reasonable choice is to not use the data. I believe that you were thinking, “if we can say that this disturbance doubles variance via random noise, we can perhaps still use the proxy”, but from what the authors have stated, this is not the case.

#2: people should have said, this is simple if you read the posts in question; at that point, not getting what Mann has done wrong is almost ridiculous. Reading some of the threads is easier than asking people to re-hash everything, as some of what you’re asking for (papers, data, etc.) has already been fully covered by Steve Mc.

1. The PDF for Tiljander03 wasn’t “a click away”–it was two clicks away. Use the link at “(e.g.)” to find my comment #237383, posted yesterday morning. Then click on “literature citations”. The third listing under “The Lake Korttajarvi Borehole” is

2. Your skill at paraphrasing correspondents is much poorer than you seem to appreciate. Your casual claims that I have said “this is simple, if you don’t get it, you’re covering for the team” (and so forth) are incorrect. From now on, please supply quotes.

3. “How about engaging on the content.” How about if you take the medicine that you prescribe to others. It is trivially simple to discover the relevant blog posts at Climate Audit and at my Tiljander-focused site.

“Did you understand my point about proxies that are questionable…”

At this point, I think it would be constructive for you to become familiar with some of the supplied background material.

I’m reading the Tjilander paper, first. I’m not going to “take the medicine” of reading through 10 different blog posts and comment threads. If you think that is a good faith method to convince fair outsiders, good luck.

The blog posts are tagged. http://www.climateaudit.org/tag/tiljander . You have the option of reading the headpost and not the article. These posts have been written from time to time as new information has become available and any individual post doesn’t necessarily re-cap all material in past posts. If the topic interests you enough to comment, I’d urge you to spend the few minutes or so reading the half dozen or so relevant posts. It would save time for you and others.

Please understand that the issue of how Mann handled the Tiljander data is readily understood by everyone other than some climate scientists. Indeed their seeming inability to understand this small issue – which has been discussed at length across several blogs – is undoubtedly the most interesting aspect of this issue.

Also I’m not trying to “persuade” you of a point of view on this. If you are able to understand the issue, fine; if you can’t, so be it.

You know in a science paper, the different papers that describe methods or give background are cited. You see exactly where a different document supports the current document. This allows pushing further were needed (and not where not). IOW ref 25 is relevant to a key kissue and ref 32 is not. In contrast, to this mechanism of showing supporting information, you just refer people to a treasure trove. In every other field, (law, engineering, history, etc.) people connect via reference note citations. If you really want do be tour de force, you could use web citations for your own documents. But you don’t even do that. You just expect people to read a collection of “research notebook” trial analyses, intermixed with phrenology cuteness, cartoons, commenters chipping in off topic, and even threads on different blogs talking to each other!

Also, I KNOW I’m well intellectually “capable” of grasping issues, Mr. McIntyre. I just don’t accept things because they validate a skeptic viewpoint. I fear many, many of your readers are so easily convinceed because they have low thresholds for things that go their way and high thresholds for the reverse. I have high thresholds for everything!

P.s You can probably have the last word, here. It’s your blog. But your views on efficacious idea analysis are in the minority. I’m back to looking at Boreas and thinking about X-ray transmission in lengthwise samples.

I dont think anybody will argue that a published article style post would be more convenient and/or convincing to outsiders. If anybody wanted to write such a summary, it wouldnt be difficult given that the information is contained in a few posts. Then again, since the information is contained in a few posts, and those few posts are easily identifiable via the Tiljander tag, it wouldn’t require much effort to read all of the work Steve has done on this topic.

If you spent as much time researching the issues as you do posting here I am sure you would have grasped the very simple issue long ago. What is strangely fascinating is watching clever people tie themselves in knots trying not to understand the obvious. But it does not do the reputation of those people much good.

If you think 10 different, wandering, blog threads, along with comments, from different parts of the internet is a helpful explanation and reasonable expectation for neutral observers to ground themselves than you are missing a screw. What field of physical science, social science, medecine, business, engineering, etc. would rely on that?

There is a large literature on just the problem that you state. How do people become aware and learn of issues that of relevance to their work? This work has been going on since at least the 1960s. One early result of that research is definitely pertinent to your comments here. It has been found that the success of research projects is inversely correlated to the degree that the workers read the literature. That is, the more that they did background reading in the relevant literature, the less likely that their research would succeed. this was found in research done in US national labs.

This result occurred because the best way to access knowledge is to consult with members of the community who are accessing current results, interpreting it and making it accessible and meaningful to members of the broader community. Researchers who accessed these knowledge gatekeepers had no need for extensive literature search since they were part of the network by which knowledge was generated, interpreted and shared. Workers who did not take part in this network were handicapped because of it and their projects suffered accordingly.

So what is available to you in the blog posts and in access to gatekeepers such as SMc is access to the research gatekeeper network in climate science. If you take advantage of this then you will be at an advantage. My advice would be to take advantage of it. However more importantly this does show that common knowledge about how knowledge is distributed is often wrong.

Condescending statements about how scientific papers are written and used are not impressive especially when these statements are contradicted by long established research results.

Just to add, that another well known result is that formal knowledge found in papers and textbooks is commonly stilted and incorrect. Practitioners use tacit knowledge that is shared within informal networks. Formal knowledge is knowledge written to be contained in short research papers. Of necessity, important considerations that are necessary for real world application but add complexity which masks the research result are left out. To contain these considerations, research papers would have to orders of magnitude longer.

Expert systems were all the rage in the 1980s. Their originators called themselves knowledge engineers and boasted that they would codify all knowledge. I read papers in which the knowledge engineers expressed concern about the effect of their systems on the human professionals in thee fields that they addressed. They indicated that the essential knowledge to diagnose and treat disease could be captured in an expert system with 250 questions. How would this affect doctors who took years of study to learn their skills. Well as it turned out, instead of 250 questions, it was more like 250 billion or 250 trillion questions. Doctors are still here and expert systems are relegated to being human assistants.

I agree with the order you’ve decided to go about this. You should read Tiljander first, then fill in with the various blog posts concerning the critiques of the paper. I think that, since most of us have been following this from the beginning and are up to speed on things, sometimes we forget how difficult it is to follow when you jump into the topic later on. Nice thing though, if you use the search bar at the top of the page, it will give you the references in order from first to last. When I need to cite Mc., this is the way I find what I’m looking for.

As far as content layout is concerned… It’s a blog, not a scientific paper. Blogs are different beasts altogether. The writing is usually of the ‘what’s on my mind today” or “whats eating my craw” type. I don’t blog nearly as much as Steve does, but I can tell you from personal experience, it’s not always as well organized as you would like. Sometime I have a hard time finding thing on my own blog.

This post contains the temperature anomaly that CRUTEM3v calculated for the 5 degree x 5 degree gridcell that includes Lake Korttajarvi.

Arthur Smith’s post Michael Mann’s errors (now closed to comments) contains the most accessible layperson’s discussion of Mann08’s use of the Tiljander proxies. The best arguments of the pro-Mann08 bloggers are on display there, for what they are worth.

Lastly, Gavin Schmidt, Michael Mann’s co-blogger at RealClimate.org, called me out at Collide-a-scape, in the guest post The Main Hindrance to Dialogue (and Detente). His best arguments are there, for what that is worth.

Re: scientist (Aug 2 22:31), Before continuing to comment and do so negatively, would make a whole lot of sense to read through the information that’s already been posted here and elsewhere about these issues. You’re making statements that demonstrate your ignorance of the subject matter, yet you are also quick to judge the work of Steve and others harshly. Doesn’t seem terribly reasonable or scientific.

You claim: “Also note, that the comments of ths study collectors are…useful…in thinking about how to use their data…but don’t rule out other interpretations.”

Ok, we’ve seen other people (including the mad rabbet) try this line of reasoning in the past to try rehabilitate Mann’s upside down use of the proxy. One simple question: if Mann did knowingly do so, don’t you think he had an obligation to explain (either in the paper or the SI) that he did so and why the interpretation of the study collector was correct?

If Mann knew there were serious issues (for example contested interpretation) about the mud sediments, he should have disclosed them. Especially since they seem to hold a lot of weight in the tree-less early recon (which I agree was one of the key claims of his new study).

He could have still published, but he would be doing the reader a courtesy to highlight this dependancy. IOW, that the study had important caveats. There probably is a value of throwing more and more questionalbe stuff together (if that is all you have) to understanding things more.

It also brings up the general issue of proxy selection and data handling. Are there other series that were improperly handled? If he is reprocessing data and coming up with new/different insights (and btw, I think this is fine per se…one of the values of the scientific literature is people using old data in new ways to extract value…why data should be archived or even better published.) Maybe he should have a varvologist and a speleologist (and such, one for each proxy area) to make sure his selections are reasonable, that data is handled properly, background and physical issues of the samples understood…heck even to help identify more series for use!

“Where the sign of the correlation could a priori be specified (positive for tree-ring data, ice-core oxygen isotopes, lake sediments, and historical documents, and negative for coral oxygen-isotope records), a one-sided significance criterion was used.”

So he clearly believed that was an a priori relationship for sediment data. I think it is also clear that the way he handled the sediment proxy in the calibration period was not consistent with the a priori relationship expected by Tijlander. To this day, despite the “flood the zone” coverage of this issue on climate blogs, we have not heard Mann or Gavin or any co-authors provide any justification for a different physical meaning. If there was a valid argument to made, I am sure we would have heard something. It is hard not to come to the conclusion that Mann made a mistake. The implications of this mistake seem debatable (though Steve makes a good argument that they are greater than originally thought). What is more eye-opening is the reaction of Mann and his defenders to the mistake. Not only do they refuse to admit any mistake, they call the criticism “bizarre”. It hardly inspires confidence.

Yes, I grasped onto that part of the PNAS paper as well. (Feel free not to answer if this is tedious.) I am still looking through the background material and papers (OP is not sufficient for my questions). It would seem that the Tjilander series were more than just sediment thickness (although I need to check that, unclear so far), but also measurments of inorganic content? So a simple view of thicker, warmer is incorrect. An analogy might be to tree rings, where not only can RW be measured, but XRD, even isotopic content. treating everything as RW would be a mistake.

Of course, the physical suitability of samples to usage is another question. (Perhaps an analogy would be tree location. If you knew that a fire or partial logging had occurred and that some of recent growth was due to lack of competion…or perhaps if you knew that a treestand was at lower elevation boundary instead of upper (Lamarche concept).

Of course, you can also imagine areas where an initial data collector has a different opinion of the usage of his data and it’s at least arguable either way. For instance, Idso collected some BCP data. And he argues that the recent growth was CO2 driven. but he has not proven his case. Others can use the data and argue other interpretations. Given Mann has competent tree ring people on his team, it seems at least that he is covering himself in terms of some perspective when using the bcps. For the varve usage, it appears that he erred by not having someone who had better understanding of these series and their backgrounds (especially given how critical they end up being to the 1300 no-tree claims, which I agree were prominent in PNAS and a lot of what made that paper additive).

“Given Mann has competent tree ring people on his team, it seems at least that he is covering himself in terms of some perspective when using the bcps”

This is not a given, if past and current usage of BCPs is any indication. Tree ring data with six-sigma pulses in it are used to show a supposedly linear relationship between temperature and tree ring width, without any discussion of how this can possibly be justified, and without discounting more convincing explanations for the large growth pulses (behavior of the tree after bark had been stripped off).

That’s an interesting point about the Bristlecone Pines, one that i have often pondered. Proven or not, there’s an unrefuted (or not contested formally) peer reviewed (that old gold standard) paper “proving” that the BCP growth patterns are due to CO2 enrichment. Mann & Co have simply assumed that the growth is due to temperature as they have never anywhere I’ve been able to find published anything that would actually attempt to demonstrate a proof (or even support for) the alternative hypothesis.

But the problems with the BCP’s are far more than that, and one of the key issues surely is that now that there is a more modern and better attested collection of BCP proxies available (Ababneh), surely those should be used for preference, or at the very least the earlier and later records should be compared and if possible reconciled. Not to do so looks awfully like unscientific data selection.

Yes there are, eg SU967. And there are other (non-Mann) reconstructions that misuse Tiljander in the same upside-down way, thereby mining for hockey sticks and writing the MWP out of the history books. If you had been following this blog you would know all this and the answers to most of your questions.

So please go and read Tiljander 2003, and type Tiljander (try to spell it right!) into the search box to find Steve’s previous posts on the subject. Then you will find the answers to your questions.

As for other series, I’m of the opinion that any series which does not have a predetermined orientation is ipso facto an improper series. Why do we believe that such a series contains temperature information, if we don’t have an idea of the physical mechanism by which temperature affects the proxy? — and if we know the mechanism, then we should know the orientation. Otherwise, aren’t we just poking around looking for circumstantial correlations? The proxy selection step will likely weed out a false proxy, but it is not infallible.

[For some (at least), we also should have an idea of the sensitivity of the proxy metric to temperature. If I’ve read Mann correctly, the proxy is blindly scaled to the temperature history of the calibration interval. Which makes sense only if there is no a priori information about the likely sensitivity to temperature. I wonder if anyone has examined the scale factors produced by the algorithm and compared them to the known range of sensitivities…]

I think this is overstating the case. Surely it would be a reasonable approach to hypothesize a relationship between temperature and some measurable quantity, without a priori certainty about the sign of the hypothetical correlation. For example, I expect that, at some (relatively high) temperature range, ring thickness would actually be negatively correlated with temperature. Surely it would be a reasonable and valid approach to test such a hypothesis by collecting data, then fitting the curves, and then testing to evaluate the predictive power of imperically derived function.

As I understand it, the problem here is that the shape of the function was assumed, not imperically established (by Mann et al, that is). The variables were the relative weighting of the proxies, not the shape of the relationships between the proxies and temperature. Consequently, inverting the sign of the correlation represents a rejection of a premise of the study, which implies invalidation of any conclusions it appears to reach (not to say proof of the opposite conclusions, of course).

As long as the relationship is predefined it certainly does not have to be monotonic. However, given the multiple variables that impact the characteristic that is proposed as a temperaure proxy, the paucity of meta data and data on likely covariates, it is going to be hard to pin down anything except the most simple relationships. Think of all the issues with the current temperature record.

QB (#237599) & Bernie (#237604),
The reconstruction method assumes that the proxy metric is related to temperature as an affine function plus noise which is uncorrelated to temperature (although the noise might not be white). That is, P = a + b*T + noise. To the extent that the parameters a and b are not constant over the record duration, but depend on other environmental factors not compensated for, the error in the reconstruction will increase. Also, to the extent that the dependence upon temperature is not linear, the error in the reconstruction will increase.

Now your example is most likely true — that is, at some high temperature, tree ring width will no longer increase with temperature, but will instead begin to decrease as the tree dries out. If that relationship holds true for the entire duration of the record, then the series is a valid candidate for use in the reconstruction. However, you’d know that going in, so you’d expect an upside-down use of that particular tree.

On the other hand, suppose the tree sometimes is in the warmer-means-more-growth domain, and sometimes in the warmer-means-less-growth domain. Then the assumption of quasi-linearity is not true, and considering the growth rate as a proxy for temperature is not valid, and the proxy shouldn’t be used. Inverting the relationship, and attempting to infer past temperature from proxy, is just not valid, because you don’t know which branch of the inversion should be used at each point in history.

Hence my conclusion that proxies without a predetermined orientation should not be used.

Shouldn’t Mann say that he interprets the proxy differently? When pointed out in a published comment that he is using the data upside-down, what is the proper response? Mann said that allegations of upside-down use are bizarre, the method is blind to the sign, one sided tests, and contamination. No mention of a different interpretation from the author.

On page 13255, Mann says: [Sparse proxies before 1500] “poses less of a challenge to the EIV approach, which makes use of nonlocal statistical relationships, allowing temperature changes over distant regions to be effectively represented through their covariance with climatic changes recorded by the network.”

Shouldn’t the greater flexibility of the EIV approach require a higher RE validation score than the CPS approach?

It strikes me that Gavin and co are flogging a dead horse with their repeated attempts resuscitate the Hockey Stick. It is strangely unscientific to repeatedly try to prove yourself right by torturing the available data rather than accept a simpler explanation. The data is what it is. Fit your hypothesis to the data and not the data to the hypothesis.

per the PNAS paper, that seems to be the base case for how EIV works (global climate field, global teleconnection, whatever you want to call it…and I’m not saying that in a pro-Mann or pro-McI sense. The calibration versus global temps has some pretty obvious pros and cons tha have been argued right from the beginning in the MBH discussion). Mann does also mention doing variants of EIV that do have local cell checks as well.

Having just re-read the 2005 PhD thesis of Mia Tiljander (not the paper so much discussed above, but the prelude to it) one has to be impressed with the professional nature of the work. There was considerable study done on magnetic properties of the cores, to a level that is beyond the usual concepts studied by geophysicists in mineral exploration, soncepts reserved for the specialist geophysicists. The understanding so expressed gives confidence in the summary findings by Tiljander that over a 7000 year term, especially –

“4. The Medieval Warm Period in AD 980-1250 is the most distinctive climate period in the whole sediment sequence identified by changes in sediment colour, X-ray density, varve thickness, LOI, as well as the isotopic composition of hydrogen in kerogen. The period is characterized by a sharp drop in the mineral-matter sedimentation rate.”

Readers should give good weight to the conclusion of the authors of the latter paper, that disturbance from roadworks etc so disrupted the pattens existing before then, that deductions from recent decades are unreliable.

Funny, all Finnish lake sediment studies I know of (Lakes Korttajärvi, Nautajärvi and Lehmilampi) show a clear Medieval Warm Period. Wonder how Mann makes it disappear….

Antti Ojala commented on the calibration of these records against instrumental records in his dissertation:

“In addition, the recent agricultural activity
has obscured the natural signals of physical varve
data, as shown by several authors earlier (e.g.
Huttunen, 1980; Segerström et al., 1984;
Petterson, 1999). According to Saarnisto (1986),
small lakes respond to rapid environmental
changes faster, but are more easily affected by
local disturbances. Therefore, the calibration of
the physical varve-data against instrumental
records is, in many cases, very difficult if not
impossible. The importance of multidisciplinary
studies (e.g. Zolitschka, 1998a; 1998b; Battarbee,
2000) needs to be emphasized again, because it
provides a better estimate of the timing and magnitude
of the effects of these cultural-related activities
effect on lake sedimentation. A
palaeoecological study of Lake Korttajärvi
(Tiljander & Saarnisto, a manuscript), for example,
reported that an intensive cultivation in
the vicinity of Korttajärvi began in the 16th century,
as indicated by the typical culture-related
pollen assemblages, L.O.I. and charcoal
stratigraphy. Prior to that, fluctuations in varve
composition and structure more likely reflect signals
of natural origin.”

Expert from another field: Hmmmm 2+2=4, I begin to have my doubts about this work
Tobias: You are not an initiate to the deep climate knowledge and are unqualified to determine if 2+2=4
RC commenter: See, there is absolutely no reason not to trust the consensus. You must be funded by big oil !

Who cares what he does at Deep Climate, if it’s the same person. This is the same argument RC used to shut down ThinkingScientist.

I’m following scientist’s posts with great interest, including his thought process posts that others are slagging. How often have others come here with an open critical mind? He’s shown that he’s not interested in only parroting others’ claims, whether those at RC or here. He’s working through the issue himself, and here is an opportunity for an independent confirmation of the issue at hand, or he may find other considerations that climate audit has been blind to. Either way, to me, the exercise is interesting and worthwhile.

I obviously encourage people to work through things themselves and welcome sc’s interest. I don’t think that the threads are as obscure as sc believes or else the blog wouldn’t have an audience.

There’s obviously a longstanding need for observations made in real time to be packaged for people that don’t want to wade through the threads. If I could clone myself, I would do so. I’m sorry about that, but I have only so much time and energy and most of it goes into topical posts. Some of these episodes have been written up, even in books – see The Hockey Stick Illusion, The CRUTape Letters, The Climate Files. The Tiljander episode would make a nice piece for another Andrew Montford or Montford-style essay along the lines of Caspar and the Jesus Paper, if and when he ever gets time.

OK, point taken, Tesseract. scientist’s haughty tone is one of the things that attracted my (and others’) ire, but it’s immaterial to the issue at hand.

Perhaps s/he will come up with the first cogent defense of the performance of Mann08’s authors with respect to the Tiljander proxies. That would be real progress.

After reading Tiljander03, I suggest that scientist walk through the Mann08 treatment of the XRD proxy at my “Jarvykortta River” post. The graphs and quotes from Tiljander03 make the problem (as I understand it) quite clear. S/he can download the proxy records and work with them, if that helps.

I’m merely a casual reader of other’s arguments with an appreciation for quality confrontation but his verbosity is shot through and through with repetition. I don’t doubt the word count could be reigned in to half of what it is currently on this topic but above that, I hope he keeps it up! His part in the peppery exchange is appreciated and something that is sorely missing in the theocracy that is RC.

Hopefully this is not OT. If so please feel free to delete.
As of this writing, things have gone very quiet at RC. In the last 30 hours, there have been only 5 postings on the Montford Delusion posting, compared to 20 on the more recent 35th Birthday posting. The postings seemed to stop after Steve posted up this thread. Strange that!
In addition, as if in rebuttal to the substance herein, they have posted an addendum from the author of the recent PNAS Paper claiming authority for good climate scientists.

I do not think that this is OT Bernie.
I’m not a scientist, but because of my involvement with health care, I can relate symptoms at RC to very common effects of food poisoning. In short it works like that:
Contamination > verbal diarhea > imodium(Steve’s post)> serious constipation > laxative. The cycle will repeat itself until contamination is removed.

In the past they have simply closed comments. They are certainly still letting one insider’s comments through. With your statement, at least 3 people have unsuccessfully tried to post. Frankly I can’t think of quite what to say so I have not tried again. A couple of my comments did get through.

OK. I read through the Boreas paper. Most of the Mann paper. And skimmed the thesis. I did NOT read the evolving blog debates (in various places: RC, AMAC, Pielke, CA, Spaghetti (often talking to each other).

Some general impressions.

-Seems like the parties agree that the no-tree chronology is dependant on the Tiljander proxies.
-Mann seems to have had an overly simple conception of the Tiljander series (bigger number=thicker layer=warmer year). The actual proxies were not just thicknesses, but measures of content.
-Thus, he likely used theses series without enough understanding of their limitations.
-So he probably at a minimum, should have informed the readers than his chronology was dependant on a new geo-isolated set of proxies and that they were themselves debatable. (But I think his failure was a mistake, not duplicity.)
-I would be interested if he thinks the varve series are “good”, “debatable” (i.e. equivalent to the bcps), or completely unsuitable.

Some more general impressions:
-not impressed with the Tiljander work in terms of a decisive explanation of the sediments. She does not construct a temperature series. Has a LOT of qualitative references to other studies and comparisons like ‘a lot of gray in period X’ rather than numerical, statistical statements.
-I don’t understand (this may be my limitation) the issue of LS, DS and XRD and wonder if they are all independant or how they would be physically resolved to show exactly from a compositional standpoint (both content and overall density) how these measures are driven. IOW, you have really 2 metrics: physical density and inorg/organic fraction. No?
-I’m concerned about the issue of compaction. How is this addressed? (and if this was addressed in a comment within one of the 20 different blog threads, this is not my “bad” for not reading it, it’s a flaw in having to weed though so much spinach to find the meat.)

A couple more philosophical things:
-I don’t like the Mann habit of writing so much of the paper within the SI. Would be better served by dividing things up, or by picking an outlet less prestigious than PNAS, but where completed papers can be written. Much of the SI text is really “paper text”. And papers are archived literature, immutable and built on by new papers and corrections and the like. SIs are too informal and too much controlled by the author.
-blog posts are even worse. Climate Auditors ought to write their stuff up in concise, cartoon-less and joke-less papers for Climate of the Past Discussions.
-The two above are for the purpose of the reader and the field, to benefit most. But would also serve the authors themsleves to better sharpen their own understanding.

—————-

Note: all of the above is based on a few hours of reading. It’s possible that more time would give different impressions and especially clarify some of the physical questions I have. However, I don’t think this is a sign of “no brains”, but more one of being honest about what it takes to really check stuff out that is alleged on Climate Audit.

Oh…and the Tiljander thesis is not that great as some people are saying. Since it follows the format of European Ph.D.s, you have to actually get all the papers she wrote. That’s not to say anything wrong with that method of doing a Ph.D. Just that the thesis itself is relatively non-sufficient.

Interesting points. Creating and validating proxies is a messy and complicated business. How about the additional question of how come Mann used such a problematic proxy. If you could spot all the issues with this proxy in a couple of hours, how come Mann et al could not? Was it by any chance its seductive shape? Second, given the obvious limitations, how do you explain Mann’s reluctance to acknowledge the direct and indirect issues that the inappropriate inclusion of a flawed proxy raised? Thus we are back to the presenting issues identified by Steve in the original post.

I don’t know if he was seduced by the impact of the new proxy and a little self-blinded to the limitations of it. The general impression I have is failure of sophistication rather than one of duplicity (e.g. he seems to regard all the varve series as thickness although they are not, include compositional metrics (or am I mistaken here!?) But of course, maybe he was less likely to dig into it, given that he thought it helped. HArd to say, really.

I think my ability to read the issues with the new proxies was helped by all the previous discussion.

I think if Mike stays in the meta-assembly of proxies business (which he should, it’s his expertise), that he needs to become more sophisticated in physical understandings and in using co-authors (no perfect answer here, since we can’t expect one man to know everything, but it will affect the quality of his work, the extent to which he can screen inputs).

I think he would also be helped by writing longer papers in less prestiguous journals, by doing more sensitivty analyses and more full factorials of method/data variations.

I haven’t followed Mike’s “reluctance to acknowledge” so hard for me to comment in detail. Wanted to start with the science itself before getting to the “who said what, when in the blogs, how were corrigendums handled when issue”. My GUESS would be that he is probably too slow to correct himself. Also that people here are hurting the process by not writing clear analyses and papers, by mixing in valid criticisms with invalid ones. Mixing in snark with real technical commentary. Probably plenty of room for each to easily improve without expecting perfection, either.

I read the Tiljander paper and she is quite clear about the anthropogenic influences. On page 9 she noted:

“The lake was quite badly polluted by waste waters in the 20th century, but since the loading of polluted waters stopped in the late 1970’s, the quality of the water has improved.”

And on page 24

“Since the early 18th century, the sedimentation has clearly been affected by increased human impact and therefore not useful for paleoclimate research.”

Tiljander may or may not have been aware that Lake Korttajärvi was partially drained by farmers and two smaller lakes were drained completely upstream. This was a common practice in Finland in the 18th and 19th centuries to create new farmland. The geological survey of the area does not state how much the water level dropped.http://www.gtk.fi/data/mps/321206.pdf

1. The procedures in Mann08 for both CPS and EIV absolutely require calibration of all proxies to the instrumental temperature record, 1850-1995.

2. None of the four Tiljander proxies used in Mann08 can be meaningfully calibrated to the instrumental temperature record, the result of progressive contamination of any climate signals during the 19th and 20th centuries by local activities (farming, peat cutting, road building, bridge reconstruction, lake eutrophication).

I think you think we are in more disagreement than what we are. Probably both an issue of my verbosity as well as your attackdoggedness.

1. I accept your assertion, noting that you no longer specify “local”.

2. The proxies can (I guess) pass calibration mathematically…since…err…they did. The problem is that the physical basis for the use of the proxies is either invalid or severely questionable since they were not simple thickness series and since Tiljander says recent years suffer from bridgebuilding, landusage changes, as well as lower consolidation.

3. I don’t know what you mean by “faux” calibration. If you mean what I said in (2), that is passes mathematically, but physical relationship not reasonable (or highly questionable) than fine. I wouldn’t use exactly that word: faux calibration. The issue isn’t per se in the calibration being done improperly mathematically (or maybe it is, but that’s not what we’re discussing) but just that the papers related to the samples say that they are inappriate to validate.

——————–

I’m not sure I can give you much more. Since I already said as much a while ago.

Attackdoggedness, why don’t you print this thread off and show it to your mother or girlfriend. Perhaps she’ll have the patience to explain the concept of “civility” to you.

1. I shouldn’t have to type “5 deg x 5 deg gridcell calculated CRUTEM3v anomalies in some cases, calculated global CRUTEM3v average anomalies in other cases” whenever I write a comment.

2. Yes, all four of the Tiljander series could have r values calculated for them… mathematically. Yes, the problem with all four proxies is their post-1720 contamination with non-climate signals.

3. “Faux” means “false” in French. You are correct, there does not appear to be a reasonable link between the (arithmetically correct) correlation that Mann08’s authors calculated between the dependent variables (the contaminated data series, 1850-1995) and temperature.

> I’m not sure I can give you much more.

Here’s the standard you set for yourself, upthread.

The key question to me is what sort of “questionable” is Tjilander? Is it a complete mess, that all sides agree should NEVER be used, no way no-how? Or is it sorta more like the tree-rings, which mayb have utility, but are in question.

[snip]

So if Mann (or you) see Tjilander as equivalent to bcps, I think you are being a little unfair to him. If Tjilander stuff is WELL WORSE than bcps and just something to never, ever use…then Mann would not be answering criticism properly to do the pea-thimble, one at a time sensitivity. Instead of evaluating sensitivity first, the key thing for him is to say are the sediments absolutley awful or just kind of like bcps and have some hair on them. If absolutley awful, then of course, he should pull them and then it does affect his ability to do tree-less recons (after losing the Finn sediments).

My impression (and I’m being honest about my level of knowledge as an outsider trying to decide fairly) is that Tiljander stuff is at a minimum questionable. I don’t think Tiljander can really explain the sediments herself, so it’s not a no-brainer in terms of “only her word counts”, but that her comments need to be taken very seriously. I would probably fall in the camp of “nobody has a good handle on what that series means. I just did not think the Boreas paper was good…way too handwavey…and then of course Mike hasn’t even addressed the physical issues at all. Then when you add in that this field seems even more new and evolving than tree rings? If essentially all varveologists (maybe those not Finn group) agree that the samples belong in the “complete junk” category, then I’d be inclined to take the appeal to authority. [Otherwise, I’m forced to read all the references to methodology from Tilj’s paper, get a textbook, etc. to drive myself out of the middle bucket.]

And that to use the series, since they were so crucial to the result, Mike should have disclosed the dependance of results on that proxy particularly, his different usage versus the data collector, etc.

I’m also a little concerned by some other issues.
1. That a substantial part of his paper’s new results depend on one set of geographically isolated samples (even if they were in the “good” bucket)! It’s on place in Finland!

2. That CPS doesn’t work.

3. And that the samples passed correlation screening (does this mean that the tests aren’t tough enough (not enough wiggle matching, joining two linear trends? And I admit to not knowing how to settle this statistically, just highlighting a question). OR does it mean, that really Tilj was WRONG to think that one could not get a real temp chronology out of the samples and too timid and should have taken a swing at it instead of being dissuaded by that 1999 farmer’s comment? Even if so, it still seems that Mike ought to then publish his own paper, just on Lake K.’s sediments, using Tilj’s data, but giving a different interpretation.

You’re totally missing the problem of the contamination of the sediments by non-climatic factors such as bridge-building. Tiljander stated clearly that the sediments were contaminated in the modern period. The problem with Mann et al was that they ignored this warning.

This is an entirely separate issue from whether the sediments meant anything in the earlier period either. There are a number of posts at the site about varve-ology, in which individual sites used in Kaufman et al 1009 were examined. But that’s an entirely different issue from the very simple one about Mann’s correlation of sediments from Finnish bridge building with global climate fields – something that may qualify as a classic example of spurious correlation, up with Yule’s original alcoholism and C of E marriages.

Yes you did practically ignore it, you’re being less than open about it. You are implying that it would be OK for Mann to leave the Tiljander proxies in, provided adequate caveats were expressed. That means you have not understood the issue. You ignore the point that the methods used require calibration, and contaminated proxies cannot be reliably calibrated. Therefore regardless of caveats expressed, until demonstrated to be able to be calibrated those proxies cannot be included in good faith.

Nice work on running down Tiljander herself too by the way, of course she’s unlikley to have a good handle on the varves she’s studied for some time is she.

It’s ALWAYS been an issue of whether the samples were contaminated. The question is are they definitely screwed up, definitely not, or unknown. I pointed out the analogy BCPs and Idso claims on reasons for growth as an analogy a while ago. If you can’t grok that…well…I let you think what you will of me.

Scientist, and I commented on that as well, you get a point that Michael Mann and the entire pro-AGW group who post at Realclimate have ignored for over 10 years. I have long given up trying to discuss the problems with BCP proxies with anyone on the pro-AGW side of the fence. They believe it has been settled by the argument best articulated in various forms at Realclimate which is that those proxies must be included because otherwise the method doesn’t deliver the right answer.

On Tiljander (the proxies that is) I suggest you’re trying too hard. We have only one set of data and there’s no other source (as far as we know) available. To attempt to justify the inclusion of this data in a way contrary to our only source must surely require at least some form of proof, be it only a logical argument based on some physical mechanisms. I assert you cannot make any scientific claim for the inclusion based on the matching of patterns via a mathematical method without some underlying explanation. Otherwise it is just as valid to claim that the increasing trend in UK marriages (say) between 1900 and 1970 (again, for example) can be calibrated against some other set of data and hence represents a valid temperature proxy.

Do you think it reasonable for the standard of inclusion to be “it’s OK unless you can prove otherwise” on questionable data ?

There are zero perfect proxies. Would you eliminate them all? I don’t think all should be included or all excluded. This is a tricky issue. You lot should not try to get rid of the stuff you don’t like extra hard, nor should Mann do the reverse. I made my three buckets as a sort of simplification of what is a spectrum. I think at a minimum, the physical concerns with Tiljander should have been better known by the authors and discussed in paper, especially given the crucial role they have for the early no-dendro EIV recon. Perhaps they don’t belong in at all, but I don’t know enough to say that right away. I mean some here want to get rid of the bcps…but it’s at least possible (maybe even plausible) that they are responding to temps and have done so for a while (the opportunistic trial of sheeps, dry lakebeds, barktype, precip, bad sample versus resample (Ababneh), etc. came acrross as a willingnes to believe in anything wrong with the proxy in a rather hopeful way to get rid of them. Similar behavior with Gaspe.

I think you need to be careful not to use bad stuff or to be prone to grabbing series to support a point of view (Mann, maybe), but also wary of skeptics trying to go after whatever proxies they can with selective criticism. It’s a type I/II issue. You can have a false negative and a false positive. Can screen in bad stuff or screen out good stuff.

For something to be a “proxy”, it has to be shown to be a proxy. Something doesn’t become a “proxy” merely by being a time series.

If a “proxy” is supposed to be uniquely important, then you should be sure that you understand whether its behavior is properly understood. You’d do that in any industrial situation before relying on it.

Ababneh’s failure to replicate Graybill’s chronology is very relevant. Same with the unreported resampling of Gaspe, also with different results.

Multiple reconstructions depend on Graybill’s samples from the 1980s. Ababneh got a different result in a more comprehensive study. It’s the job of specialists in the field to reconcile the results. Until they do so, the Graybill results shouldn’t be used. Dead simple.

The profoundly “unscientific” handling of data by so-called scientists is highly problematic. Hence the reason for regarding their work as pseudo-science rather than “science” and thus the derogatory term phrenology.

These are very elementary issues and the “scientists” in question have a responsibility for dealing with them in a professional standard regardless of whether I choose to interest myself in these issues or not.

1. You’re not going to get anywhere with neutral parties by eschewing publication (which puts you on report, crispens your thoughts, makes it easier for people to read, archives, etc. etc. etc.) and talking about phrenology with artoons of pantless people. The former is a bigger strike than the latter. You take it too easy on yourself and too hard on the opponent. It’s not fair or efficient. Your blog method of arguing a position over the years would never cut it in any technical organization.

2. Maybe, maybe not. Some of you lot don’t like thermometers either, after all. The Mannian method is more of having half a rationale and then throwing a bunch of series into the hopper to churn them. That’s a different issue, methodological really, than the Tilj debate. How tough are you going to make the proxy tests and how many good series are you going to screen out along with bad ones? I still recall your halting refusal to realize that passing a 3 period test is implicitly harder than a 1 period test and saying a “proxy is a proxy” as if we should set up 10 periods or something as the judgment. It’s not a digital situation. It’s not yes, no.

3. Maybe Ababneh got it wrong. Maybe Tilj did too. Maybe that’s why they don’t back up their work. Anyway there is always the Mcintyre expedition and associated poster which did get good Graybill replication! And maybe you should have listened to me a long time ago when I said resampling from the identical trees to extend is actually less valuable than resampling the same population but from new trees, to both extend and validate.

That’s interesting. Wouldn’t things be a lot stronger if she were banging the drums for how the series was uncalibrateable? If she were giving more details on the bridge and the road and the farmer from 1999? Maybe she’s in the middle bucket as well?

Sc, you seem to take the position that a non-specialist like Mann has the right to use a data set whether or not it has been demonstrated that the data set in the usage has been established to be a temperature proxy. Surely a “scientist” would require the opposite. Cavils about Tiljander’s thesis and paper do not serve your point. If you don’t think that the paper justifies the data set as a “proxy” for temperature, then you’ve proved the point that it shouldn’t be used.

Again, the interesting sociological question is why “scientists” have such a hard time coming to grips with a point that statisticians, economists, lawyers, accountants understand without difficulty. And then blame the messengers. Not just you, it’s an ongoing phenomenon.

Scientist, she probably wants to have a continuing career. Disputing anything with Michael Mann is a quick way out of the funding gravy train. Hint: Try to get in touch with Linah Ababneh and ask her about her Bristlecone work.

I remember you posting that before. I found his translated statements rather undetailed to the matter at hand and rather general in faultfinding with climate scientists. It’s something though. I guess. I wonder what Dean at USGS would say. Or Tiljander or the PI (her professor).

Steve: I asked Tiljander about it and she sent me an email confirming that the modern portion had been contaminated. There’s nothing to argue about.

McIntyre (VoG): In your opinion, there is nothing to argue about. I still think there is more of interest here. The issue is one of physical interpretation versus brute force calibration by mathematics. If things were not “going your way”, I doubt you would think an individual email of one person was dispositive. This reminds me of the NAS panel, where you simultaneously noted their lack of deep analysis (“winging it”) but ran with a text snippet that they said that fit your cause (‘avoid stripbark bcps’).

A deep discussion by Tiljander would do much more to sway me than a quick email to you. Same with the PI. Same if we had some outsider like Dean way in and give his thoughts on whether the series is hopelessly compromised.

This also reminds me of the Idso paper, where he collected data and now you want to go with his interpretation as some sort of “precedent” weighting, when just READING those papers shows that he did not prove his case, just speculated on a physical rationale!

The idea that I relied on one email is absurd. SOmeone inquired about whether Tiljander had been contacted and I said yes.

Tiljander said in her papers that the data had been contaminated by modern disturbance. I have no reason to doubt that. The onus on justifying the use of this proxy in an Mannian algorithm rests entirely on the proponents and thus far no justification has been provided.

You also misunderstand the point about the NAS panel. Again the originating authors had said that the bristlecone growth pulse was not a temperature proxy. MBH coauthor Hughes said as much. Ironically, many bristlecone series fail the correlation screening of Mann et al 2008. In this case, Pete H and I looked at some aspects of strip bark – something that the specialists ought to have done. The 6-sigma pulses are a big statistical issue that haven’t been dealt with by specialists.

If people propose to rely on these proxies as having particular importance, they need to be justified. Arm waving shouldn’t cut it.

Can somebody tell what is in dispute here. Scientist and SMc agree that the Tijlander “proxy” has is doubtful in various ways. The Mann reconstruction is dependent on this “proxy”. Therefore the Mann reconstruction is in doubt. This seems to be agreed.

SMc points out that specialists, including Tijlander, indicate that the “proxy” is contaminated and upside down from the orientation used by Mann. Scientist, who is not a specialist or particularly knowledgeable about the subject, wants more evidence than the opinion of multiple specialists who have studied the matter. He/she offers no evidence beyond this assertion.

What is the import of this debate. Either way the Mann reconstruction is doubtful. Why is this a dispute worth having?

TAG: I agree that the recon is doubtful. Some sort of statement that the no-tree recon becomes dependent on new records which also have physicality concerns should have been in the paper. I’m also concerned by the failure or inconsistency of CPS. Mann acknowledges it and give somes rationales. But it’s implicitly making the case less strong if it doesn’t survive that methodology choice.

I’m not sure what you expect. From what I can see, that paper is about on a par with similar ones. Hank Roberts had a neat link to a report of German lake whose sediments clearly recorded the Younger Dryas, but that was a pretty drastic change of climate regimes (and it’s behind Nature’s paywall). For context from 5 other Finnish lakes, pull Jarmo’s PDF.

> so it’s not a no-brainer in terms of “only [Tiljander’s] word counts”, but that her comments need to be taken very seriously.

Agreed.

> [Prof. Mann] hasn’t even addressed the physical issues at all.

Agreed.

> Otherwise, I’m forced to read all the references to methodology from Tilj’s paper, get a textbook, etc. to drive myself out of the middle bucket.

Try looking at the graphs of XRD in the Korttyjarva River post. For Mann08’s authors to flip two of Tiljander03’s correlations around… those are pretty extreme changes in interpretations. Also note that Kaufman09 (Science) corrected his MS to return the relevant proxies’ orientations to those proposed by Tiljander03, when he was made aware of the issue by McIntyre. Mann09 (Science) did not. So we have the spectacle of three recent and near-contemporaneous papers: one revised to be concordant with the relevant authority, and two that are discordant. Can a given value in a lakebed varve–say, an increase in Lightsum over time–mean Cooling (Tiljander03, Kaufman09) and, also, mean Warming (Mann08, Mann09)? How would that work, exactly?

> 1. That a substantial part of his paper’s new results depend on one set of geographically isolated samples…
> 2. That CPS doesn’t work.

I’m uneasy about the methods, but on an intuitive level. FWIW, it seems to me that worthwhile commentary has been written by Steve McI & RomanM (CA), and Jeff Id (the Air Vent); check those sources.

> 3. And that the samples passed correlation screening…

The 1926 paper that Spence_UK links to provides an answer to those questions.

With respect to (3), I would not personally use the term “faux calibration” – I think I would tend to refer to “spurious correlation” or “nonsense correlation”, two terms which have been discussed on this site since the beginning of the blog, and that has been discussed in the statistical literature for more than 80 years.

Here is an early paper on the topic which was discussed extensively in the early days of this blog.

And while we are being pedantic Yule actually distinguished between “nonsense” correlations – correlations which exist between two quite unrelated variables as in the 1926 paper, and “spurious” correlations which he had identified in 1897 – where two variables are related but only because they both depend on a third variable which is not being considered. See Hendry and Morgan’s book of classic econometric readings “The Foundations of Econometric Analysis” pages 10-12 (and the reprint of the 1926 paper). The correlation between sediments and temperature looks like a classic nonsense correlation to me.

> Mann seems to have had an overly simple conception of the Tiljander series (bigger number=thicker layer=warmer year).

Not really. The authors accessed the four data series, considered the cautions in Tiljander03 and decided they weren’t crucial, then performed their screening and validation tests as described in the SI. The resulting r values are presumably as described —

0.3066 Darksum
0.2714 Lightsum
0.2987 Thickness
0.1232 X-Ray Density

All are relationships between {proxy quantity} and {temperature} are positive. The issue is that this calibration is to the non-climate-related signals that progressively affected the lakebed sediments in the post-1720 period, according to Tiljander03.

> [Mann & coauthors] likely used theses series without enough understanding of their limitations.

Yes.

> So he… should have informed the readers than his chronology was dependant on a new geo-isolated set of proxies…

If Mann08’s authors were aware of their redefinition of the relationships of {proxy values} to {temperature}, then yes, they should have done so. But since they were likely unaware of the problem, how could they have done so?

> I would be interested if he thinks the varve series are “good”, “debatable”…, or completely unsuitable.

Prof. Mann has declined opportunities to address this issue.

> not impressed with the Tiljander work in terms of a decisive explanation of the sediments. She does not construct a temperature series.

Can you suggest how she was to construct a pre-1720 temperature series, for the portion of the varve record that was least affected by non-climate local signals?

> I don’t understand… the issue of LS, DS and XRD and wonder if they are all independant…

Good question. Lightsum is meant as a proxy of mineral content, Darksum as a proxy of organic content. XRD appears to be a digitization of X-Ray film’s grayscale density, once a core of defined thickness has been X-rayed. It’s unclear to me whether the Lake Korttajarvi record should be considered “one proxy” or “multiple proxies.” (But this is a second-order issue.) For more discussion (but no clear-cut answers) on physical data that can be extracted from lakebed cores, see the PDF linked at Jarmo’s comment, supra.

> I’m concerned about the issue of compaction. How is this addressed?

I don’t believe it has been discussed in the context of Mann08; this seems like a distinctly second-order consideration. It is considered in the sedimentology literarature (no citation).

> …blog posts are even worse. Climate Auditors ought to write their stuff up in concise…

Please provide a link to an example of you performing up to the standards that you repeatedly demand of others. Seriously–on a climate-related topic, your best peer-reviewed article, or review, or poster, or Journal Club presentation, or term paper, or blog post, or blog comment. You can post it at BitBucket.org and supply the link. Enough chatter–show off your best deliverable. If you can’t or won’t, your failure to perform should be embarrassing enough to get your to tone down your jive.

1. When I said he should have disclosed the concerns, I didn’t mean that he knew it and failed to do so.

2. I don’t understand your comment, first you say that he was well aware of the limitations (in SI) and then you say, not.

3. I have not written any such gold standard papers in climate. I will continue to assert the superiority of the real literature over blogging, though. First, the point is immaterial to my performance (for example murder is wrong, even if I murder), so why do I have to show an example of my work. And I would even say that my commentary with you all here is an example of the problems with blog style discussion. That the time spent writing a real article would crispen my thoughts, make it easier for others to read, etc. Second, the concept applies across fields (why do you say to show an example in climate specifically?) Third, there’s a pretty rich literature on the superiority of archived literature in driving people to crispen their thoughts and in making it easier for readers to assess, archive and search. Fourth, my personal experience (which is none of your damned business) is that clear writing is darn hard work, but it sure drives clear thinking and it sure helps decision making. So…you have not convinced me to change my VIEW. On the tone, I will try to work on that, but I suspect the view will irk you regardless.

> 1. When I said he should have disclosed the concerns, I didn’t mean that he knew it and failed to do so.

Agreed.

> 2. first you say that [Mann] was well aware of the limitations (in SI) and then you say, not.

Mann08’s authors were clearly aware of the issues, as they discussed them. They then went on to use the data. Either they knew they were bad (very unlikely, IMO), or they figured that the problems weren’t that severe after all (consistent with what they wrote in the SI). One flag they seem to have missed was that the calculated correlations for lightsum and XRD were inverted with respect to Tiljander03’s interpretations. If they’d noticed these two “upside-down” interpretations, they would have been obligated to describe them. Yes?

> 3. why do I have to show an example of my work.

Because you complain incessantly about the shortcomings of others’ work. Talk to some ex-waiters: most have a far more nuanced view of restaurant service than you evince here.

> my commentary with you all here is an example of the problems with blog style discussion.

Agreed. Something you could improve, fairly easily.

> the concept applies across fields (why do you say to show an example in climate specifically?)

“So we have the spectacle of three recent and near-contemporaneous papers: one revised to be concordant with the relevant authority, and two that are discordant. Can a given value in a lakebed varve–say, an increase in Lightsum over time–mean Cooling (Tiljander03, Kaufman09) and, also, mean Warming (Mann08, Mann09)? How would that work, exactly?”

What’s your opinion, scientist? Can an increase in a Lightsum varve proxy over time be interpreted to mean Cooling by some authors, while the same trend is interpreted to mean Warming by other authors?

FWIW, my own answer is “No.” Either Tiljander03 and Kaufman09 are wrong, or Mann08 and Mann09 are wrong (of course, they might all be wrong).

On the science, per MikeN, is “one or the other” wrong? Stoat blogger William Connolley didn’t think so. On this point, he said, “[Kaufman] is right and Mann is right.” (inline remark at Comment #16).

Incidentally, Kaufman09’s authors used a splicing procedure so that they could avoid attempting to calibrate the Tiljander proxies to the post-1850 instrumental record. That is why they could decide to use the Tiljander03-concordant orientation for the proxies on an a priori basis.

Re: Kaufman, they perform some sort of two-step splice/calibration; I don’t know more than that. You’ll have to read the paper.

Re: insults, I think your gratuitous snark in this thread has been offensive. It distracts from discussion of the science. If you meant it: I think you should exercise better self-control. If you didn’t: again, consult your mother or your GF for advice. This is a truce. Return to your bad habits and I’ll press again. You think your person is sacrosanct while lesser mortals are fair game, well tough.

Yeah…and I was reading something saying that snowmelt driven width series were seen more as precip than warmth proxies (summer growth being the opposite). Obviously precip is a confounding factor for Tilj although hers is not just a thickness series and maybe she’s right that warmer winters have less snow, etc. (would prefer a mathematical presentation of that, rather than qualitative).

In theory, a rain proxy could be a temp proxy if they have strong correlation (or anti-correlation). Just like in theory teleconnection is possible. It’s a more tenuous physical argument though. And when you mix in the calibration versus global temp vice local, get another concern for series with less strong physical rationales.

1. You don’t understand the concept or you disagree that it occurs? You can’t concieve of weather patterns? I’m not quite clear what you mean by a quantified definition. One can set up a quantified relationship! Will have some noise terms and some correlation coefficients and the like. But you can set it up. I mean it’s just analagous to proxies themselves. The coral is a proxy for a thermometer. During an El Nino, warm pacific is correlated with cold US East Coast.

2. The case where teleconnection might be “superior” to local is where local is missing. Just as a proxy treering is superior to a thermometer when you lack temp records going back far enough or a time machine!

——————

None of this is said to argue FOR teleconnections or the use that Mike Mann has made of them. But just harumphing is non-additive.

Re: scientist (Aug 3 22:54), Your comments indicate that your knowledge of statistics is weak. Unfortunately, this weakness applies more generally to how statistical methodology is used in the climate science community as well. Let’s look at your comment (in a slightly different order) to indicate why I say this. I may plagiarize myself from a comment I made in the phrenology thread a little more than a week ago.

I’m not quite clear what you mean by a quantified definition. One can set up a quantified relationship! Will have some noiseterms and some correlation coefficients and the like. But you can set it up. I mean it’s just analagous to proxies themselves.

Statistical analysis does not take place in a vacuum. You need to have a statistical model. When you are analyzing a physical situation, identify the variables involved, including variables which may represent “random” effects in the physical situation. Explicitly state the quantitative relationships (usually equations) which indicate how these variables relate to each other including whatever parameters may be part of these relationships. The model needs to properly reflect the underlying physical structure in order to have any chance at an end result that is meaningful with properly estimated parameters and measures of uncertainty for those parameters.

Your arm waving statement “One can set up a quantified relationship! Will have some noise terms and some correlation coefficients and the like” indicates just how little you understand about the importance of a proper model. What exactly does “analagous to proxies” mean, if anything? These are very naive words which betray a lack of statistical understanding.

This is where climate science has also been particularly lax. What exactly is a “climate signal” that Prof. Mann keeps looking for in his reconstructions? Spell it out mathematically. In tree ring chronologies, the traditional method has been to divide out a growth curve and then to average out the results to form the chronology. is this a good way to do it? Are the error bounds that are calculated for the chronology proper and realistic? What climate scientists don’t seem to understand is that in every analysis situation, they have implicitly specified a statistical model and that the correct interpretation of their statistically derived results depends on an understanding of the details of the model.

You don’t understand the concept [teleconnection] or you disagree that it occurs? You can’t concieve of weather patterns? The coral is a proxy for a thermometer. During an El Nino, warm pacific is correlated with cold US East Coast.

No one denies that weather patterns exist and that something happening in one portion of the globe can have effects elsewhere. What the climate scientists (and you) don’t seem to understand is that for teleconnections to be usable in a analytic fashion, there must be a specific real identifiable physical effect which operates at the distant location and it is that physical effect which produces the quantitative result on whatever we are measuring.

In my earlier comment, I was addressing the use of global temperature to calibrate a proxy when local temperatures were available but the proxy has not responded to them. What physical unidentified effect at the local site was the proxy responding to? Assuming that this unidentified (non-temperature) effect is related to the proxy measurements in an EXACTLY equivalent quantitative form as the local temperatures are related to other proxies elsewhere (remember the existence of the above mentioned implicit model) is science fiction and lends itself to the cherry picking of spuriously correlated series.

What about your weakly stated example with the coral? Details are important. Am I trying to reconstruct the temperatures on the east coast using the coral? Suppose that I think that I have established some sort of quantitative relationship between local temperatures and the coral. Do I assume that the teleconnection translates this exactly to the east coast? Obviously, not, since you say the temperatures are reversed. What is the relationship? Does it keep the same form or is the functional relationship more complicated? What is the statistical model? Without understanding and identifying the mechanism of the teleconnection, there is no way of knowing whether the statistical results are realistic and not yet one more case of spurious correlation.

RomanM: I agree that the model is important and already said that one can imagine justified and non-justified teleconnections. IOW, good models and bad models. The idea of a proxy is really analagous to the idea of teleconnection. Whether the teleconnections are justified, is a worthy issue to address. But just scoffing at the concept is not helpful. It’s like people who scoff at proxies in general. You have to show how the proxy is poor or the teleconnection is poor. (Or even if you want to put the onus of proof on the other side, to show that they are good.)

But just scoffing at teleconnection like a nasty word is like scoffing at “treemometers”.

I don’t know. Maybe Mann is really pulling signal out of noise with his mining methods. I don’t have the stats background really to judge him, and am very open (maybe even Bayesian believe) that he mines too much. But I’m at least open to the idea that his more complicated methods are the way to squeeze most value out of what we have. [That said, and again, I realize this is out of my guild, but I’m kind of intrigued with what Christensen and Smeardon and Huybers are doing.]

People with experience with financial markets and stock markets know how tempting “systems”. There are many financial time series and many correlations. The term “proxy” had uses in economics before paleoclimate. Just because someone says that something is a “proxy” doesn’t mean that it is.

Nor have I scoffed at the theoretical concept of a “proxy” as you allege. Isotopes in some circumstances seem to be effective proxies, but their use on a 1000 year scale has not advanced as much as people would hope. I’m intrigued with some high-resolution ocean sediment studies. While I do not reject the concept of a “proxy” theoretically, I am very critical of specific attempts to implement the idea – especially data snooping and ex post correlation picking. Or of the quality of individual proxies e..g Graybill bristlecones, Gaspe, briffa Yamal. This is entirely different from contesting the concept. (This is not to say that individual readers haven’t taken more extreme positions from time to time, but is the core CA position taken by me and the major commenters.)

You have to show how the proxy is poor or the teleconnection is poor. (Or even if you want to put the onus of proof on the other side, to show that they are good.)

This is where you’re clueless. The ‘other side’ put forth the theory of climate teleconnection, the onus will always and forever be on the ‘other side’ to prove that it exists, is measurable and/or falsifiable. They haven’t done it even by your misguided standards. The proof of their theories of teleconnection being poor are out and there, you just refuse to acknowledge them.

Sure there are dangers in systems. There’s value in them as well. I’m very comfortabel with discussion of methodology concerns, but would be much more impressed if you quantified your concerns, showed them in more detail and rigorously (yes…a higher standard than you’ve done so far), and showed some concern for what you lose by not using systems. That and disaggregated issues.

I was addressing the mass of your core commenters. And you can’t take some stand of what the mass of the commenters say (or if you do, I can contest it). And I was definitely adressing the hoi polloi.

Well of course one or the other is wrong. However, his point is that it may be the case that it is not yet known which is the wrong answer, and therefore justifiable for a scientist to use ether interpretation.

My issue is that when the upside-down charge was made, he made no reference to an alternate interpretation, just that the accusation was bizarre given the paper’s methodology.

I think it has to be one way or the other. I just was pretty underwhelmed with the Broseas article, so I’m much more in the “who knows” camp. Kaufman just reversed the relationship to correspond to Tiljander’s authority (not an independent examination (my impression)). And Mann08 and 09 are presumably based on the same rationales. [I don’t know Mann09 btw, this is first you’ve thrown that in.] So basically, you have a physical argument from Tiljander about minerals getting washing in in the spring (and coming from big snows, which come from cold winters, along with warm summers giving lots of plant goo) Also, the physical argument of the bridge being significant. Versus the Mann orientation from calibration versus recent pattern, just based on math crunching.

I’m pretty open to either possibility being right. Some things that would help me convert to more surety: an assessment in the modern period of an undisturbed Northern lake and a correlation of the different metrics (LS, DS, XRD and thickness) versus temperature.

And this is just an aside (and might be changed by learning more, blabla) but I can’t imagine that all four of the metrics are really independent. Like if you had a 3-phase material: AxByCz. And you specify the % of each material (A, B, C). It’s really NOT 3 factors. But 2. Since %A+%B+%C=100%. Seems like what you really have in those samples is thickness and inorg percentage. That’s if compaction is a negligeble issue. If not, then compaction is a third. But i’m not getting where 4 physcial indepenent things are coming out…

> you have a physical argument from Tiljander about minerals getting washing in in the spring (and coming from big snows, which come from cold winters, along with warm summers giving lots of plant goo)

Agree.

> an assessment in the modern period of an undisturbed Northern lake and a correlation of the different metrics (LS, DS, XRD and thickness) versus temperature.

Good point. A browse at Google Scholar brought up, most prominently… that PDF that Jarmo already linked. Many people are using varved sediments for lookbacks to the Younger Dryas or the late Pliestocene, it seems. There, aeolian dust seems to be the biggest deal, not directly relevant to this Lake Korttajarvi story. Maybe somebody else knows the field?

> I’m pretty open to either possibility being right.

It seems to me that it’s not really about “either possibility”. Getting the overall orientation rightside-up (cf. upside-down) is necessary but not sufficient. The point of the validation is to establish a meaningful quantitative relationship. If, post-1720, minerals are washing in due to increased rates of bridge reconstruction (etc.), and organic goo is settling due to increasing eutrophication (etc.)… what’s the putative relationship to climate signals? Which is presumably the point of the exercise. Right?

> I can’t imagine that all four of the metrics are really independent.

The question is to what extent does the bridge and the road and the land usage interfere with the calibration period. It’s at least concieveable that one could have a bridge go up, think that it messed up the goo, and be wrong that it really didn’t.

The question is how much did those disturbances mess up the varve data (and the bridge was recent, I think, so you could see if that post 1963 data “matters”). As an aside, I’d also mention that her paper talks about other land usage issues going on well before the 19th century (farming 2000 years ago, deforestation, stoneage sites, etc. as well as changing hydrology).

If anything, I’m inclined to the verboten side of the middle questionable bucket, given the remarks of Tiljander. But her overall handwaviness, not just on the contamination but all through that paper, makes me not “snap-shut” certain when she raises QUALITATIVE concerns.

“Compression” (ie. lithification) is not a real issue here as it does not change the parameters of the initial deposition except for water content. In fact, lithification makes the core sample easier to retrieve and considerably lessens core loss. Such loss makes interpretation of the depositional environment more problematic. I have analysed the geophysical logs presented in Tiljander’s papers and agree with her estimates of minor core losses

One of the limiting factors in Tiljander’s thesis is the small area represented by the drillhole locations. This is essentially because the accessible fringe lake area itself is limited. The reason for wishing for wider geographical spread of sample points is that micro-disturbances (eg. from sudden but small surges of water released by an ice break) can be more easily distinguished from broader conditions around the lake edge

If the bio-organism layers are identified as from warmer-weather species (as Tiljander does), then bio-organism vs silicate thicknesses are seen as reliable proxies of warmer/colder conditions, in my opinion

I cannot see a 4-factor situation here,just thicknesses, organic/silicate layer contents and degree of sedimentation disturbance. But – human activity on the lake edges (especially driven piles for bridges) do most certainly interfere with the slow, delicate process of sedimentation, to the point of local destruction

Nice post, man. Thanks. I would assume that XRD is a function of both compression and mineral fraction. Also that thickness is confounded with densification. I was wondering about sampling as well. Didn’t see a map (I might have missed it) or a discussion of what happened with the other cores (if she only had time, money to look at a subsample, fine, but explain that). The different things she does not address kind of bug me a bit: the XRD/LS/DS non-independance, sampling geography, confounding pre-1700 land usage etc. That and her explanation of the chronology seemed very qualitative (look at the section on the Roman Warm Period for instance). She grabs a lot of different other observations and weaves them into the discussion, but I really didn’t get the sense of “here’s my series…here’s where it matches other people and here’s where it doesn’t”.

We haven’t talked about the mag susceptibility much here or about ashing the samples either (rather than X-ray). No real criticism of her in my comment. Just noting that that stuff was in there too.

Wondering, if you see th bridge as the key issue or the comments about land use changes since the 1700s. IOW, is the big concern 1967? 1967 and post-years? Or all of 18th-20th centuries?

1) XRD analysis is to determine both the mineralogical composition and ratio of inorganic/organic material in a sample. Compression and density have no bearing on this, nor does magnetic susceptibility

2) varves are generally regarded as an accumulation of annual “pairs” of strata, crudely summer and winter

3) in summer, when water flows from melting ice are relatively more abundant and turbulent, sand/silt is deposited along with any debris from dying organisms (light coloured stratum). In winter, clay particles are very, very slowly deposited (because these are so fine), generally with relatively little or no organic debris (dark coloured stratum). This deposition requires very undisturbed water to avoid re-stirring the particles, thus preventing deposition

4) because the deposition process is so delicate in both seasons, anything that interrupts the water/sediment flows or equilibrium in any one year will result in a deformation of the annual “pair”. If the interruptions are long-lived (farming, bridge building, ditch-digging), the deformation likely results in damaged strata succession over a considerable period (perhaps many years), making correlation with samples in other local geographical locations highly problematic

5) Tiljander’s papers may not be absolutely complete, but she knew which way is up (in the physical, strata succession sense) and also that persistent human interference around the lake edges inserted the likelihood of damaged varve succession, thickness, composition

Very helpful context, Ianl8888. I have taken the liberty of transcribing your remarks and placing them here for easier reference. Two questions: 1. when you say “In summer, when water flows from melting ice…”, do you mean “spring” or “early spring”? 2. Tiljander03 describes Darksum as representing accumulation of organic material, IIRC. You seem to imply that it represents fines of dark-colored clays.

1. My intuition would be that XRD (which I think is percent transmittance, really, in terms of the measurable, or do I have this wrong?) would be a function of the type of interposing matter and the amount of it. So, with equivalent compression, the sample that has a higher percentage of high atomic number atoms will have lower transmittance. Similarly, with equivalent composition, a sample that is more compacted (denser, more atoms per volume) would have lower transmittance. You can think of a vacuum as the limit of low compaction, where you would have 100% transmittance.

2. I got that from the reading already.

3. Tiljander says that the thinks the spring melt washes minerals into the lake. that the summer melt is organic matter (not clay). She doesn’t really prove this, although it’s reasonable and the metallography microscope pictures show mineral grains preferentially in one side and the X-ray transmittance seems to correlated with what we would expect of organic versus inorganic. There’s also some references to other previous studies, which I did not pull, don’t know if they are foundational for these lakes. In addition, there’s a recent freeze core and (I think, mind wandered) some ashing experiments. Also, I kinda missed much discussion of the type of inorganic matter (I like Dean’s stuff in Minnesota better). Not clear to me how much wind dust introduction is done versus melt, etc. Anyhow, I’m not sure you read it that careful either and not sure how me reading it even more carefully is needed. I think Amac and I “get” each other on Boreas.

4. So how do we figure out if the bridge messed up one year or all the years after? Would there be some signature to see that the “after years”, the water was still full of dirt? And you haven’t answered about the non-bridge issues. Is the bridge the elephant in the room or what about the other concerns (road, land usage, etc.)

5 and 6: Yeah, I’m kinda concerned about the pre-1700 land usage as well. The forest clearing at 1 AD, the stone age sites, farming grains, etc. All that. If you look at the Swiss Lake study I googled at zero dark thirty last night, they actually have some mathematics and say that most of what the varves tell them (for that area) is land usage, pasturing, etc. which is not purely climate driven but had independent shifts based on human technology and political issues.

5 and 6: This is just an impression, not an accusation, but Tiljanders seems more like someone who got her Ph.D. by weaving a snowball together. The one worthy thing she did was to collect the cores and get the tests run on them. IOW “make the series”. But I’m kinda underwhelmed by her overly qualitiative approach to matching the series to other events, other work. She doesn’t run integrations under the curve for her series in “warm periods”. And just looking at the stuff, by eye, wonder if you could argue a lot of stuff the other way round. That and given she never comes up with a temp series. Just a niggling hunch….but I’m not compelled by her treatment of the series she gets mathematically or in comparison to outside literature. I donno…maybe I’m being too rough…but I have that sense.

XRAY diffraction (XRD). We use XRF for field work to determine mineral composition/per cent. XRD is (typically) for lab work and is a bit more involved. see this link.
… http://epswww.unm.edu/xrd/xrdbasics.pdf

Tiljander talks about X ray DENSITY, not diffraction. The impression I had was that this was a scanning transmittance measurement along the core. Diffraction would involve 2 theta plots and all that and wouldn’t make sense as a lengthwises series with single value.

P.s. I tried a quick Google, and didn’t get a good physical explanation of the metric. Probably is one in Tilj’s references or some other article, but don’t have access right now. So I’m stating my interpretation and waiting for correction from those who are all up to speed on this.

I wondered, as you also raised the issue of minerals and identification. We use XRF, XRD (diffraction) and XRAY Density (sediment) — which is our accepted terminology — which is usually the designation in common use. But we are just concerned about Geology. …and yes it would be similar to bone density/aging which is a common use of XRAY Density scans which resolves similar issues of “growth rings”. I suspect that the XR density is more resolving compaction and particle size than element density — or identifying the elements in any way — which is more an issue XRRF or SWIR techniques. Hope that is more clear

There is no evidence that Mann’s orientation comes from math crunching. From looking at the code for the paper, Tiljander was assigned its orientation before processing, and was sent thru a one-sided test. There was no possibility of it being flipped during processing. So any inverted orientation is done manually, calibration is from looking at the graph, seeing a spike at the end, and assuming that it doesn’t need to be flipped. This is what Kaufman did, and probably what Mann did as well. No mention in the paper or in the reply to Steve’s published comment of an alternate interpretation.

Yes. I don’t know why people keep repeating this false claim that the orientation comes from the number crunching. In the PNAS paper, Mann clearly states that for sediments that “the sign of the correlation could a priori be specified”.

I have been looking at this for a while and think I have found the source of all the controversy. I have just posted at Arthurs open thread but as it is awaiting moderation I hope he won´t mind me posting it here as well.

“Hello Arthur,

May I just add my thoughts on the Tiljander kerfuffle. I have come to the conclusion that a mistake was made by Mann et al in the 08 paper. They simply did not follow the procedure as described. An essential part of the method was the screening of the proxies prior to calibration and reconstruction. They are quite clear that the particular test is dependent on a priori knowledge of the sign of the correlation between the proxy values and the instrumental temperature record. In the case of the Tiljander varves the only source of a priori knowledge comes from the original Tiljander paper which has never been contested in any literature that I am aware of.

As far I know Tiljander assigned a positive correlation to Darksum, a negative correlation to Lightsum and X-ray density. No correlation was given for Thickness. Clearly, Mann et al were quite free to contest these assignments if they wished to, and use other correlations for the screening tests but I cannot believe that they would have done this without any discussion in the paper. It certainly seems from the code that all these varves were actually given the test appropriate for a positive correlation and I can only conclude that this was an accidental mistake. Had the only known a priori tests been applied correctly the Lightsum and X-ray density would have failed screening and excluded from further consideration. The correct test for Thickness would have been the two sided one but it would have passed that anyway.

Everything else then follows from this initial error in the screening procedure. Of course, all four varves did turn out to have a positive correlation during the instrumental period and so all four were included in the construction using the positive correlation leading to all the chatter about them being upside down.

As I am just a retired electronics type I cannot offer any informed opinion about the correctness or otherwise of the original Tiljander correlations or the extent to which the acknowledged contamination during the instrumental period may have led to faulty calibration, including sign, of some of the proxies.

It would certainly be valuable to find out whether subjecting all four proxies to the screening test for positive correlation was an accident or intentional but unexplained.

Don’t forget Steve’s comment in PNAS in response to Mann’s paper and Mann’s reply. I think that should have been the starting point, as it is the most important part of the discussion. It is the linchpin of Arthur Smith’s ‘is it fraud’ discussion.

As a casual observer of this thread, I want to point out a couple of things that I hope you will think about.

1) The issue of the Tiljander varve proxies has been hashed over by a lot of technical people, here and elsewhere. Based on any reasonable argument, those proxies can’t be defensibly included in Mann et al’s reconstruction. Mann’s reconstruction algorithm spat out correlations opposite (in a physical sense) the rational for these to function as a proxy for temperature. It is a bit like collecting data on thermal expansion of stone as a temperature proxy, and after finding a physically impossible reverse correlation, continuing to use the data JUST because it correlates! This is what makes so many people crazy about Mann’s efforts: substitution of a mathematical methodology for rational analysis.

2) It took a very long time for anyone in climate science to publicly admit that two very questionable proxies (BCP and Tiljander varves) together generated most of the reported “hockey stick”… without these two, there isn’t much, well, to shake a stick at in Mann’s reconstruction. I will trust that it was incompetence rather than malfeasance which lead to this odd delay.

3) Mann and company handled the whole affair very badly from the POV of PR. Rather than engage critics and sort things out, all we heard were declarations of “bizarre” reasoning. And much later, “it doesn’t matter”, and “its not important in the big picture”. Please. It doesn’t take a lot of horsepower to see the problems with Mann’s methods; high school science students can grasp that you shouldn’t use data which is 180 degrees from the expected orientation. It doesn’t take a mental giant to see that a MWP as warm as today means the current temperatures are less than extremely alarming. The in-your-face arrogance shows a terrible lack of respect, and reflects poorly on those involved.

Can I suggest something? Take a look at Google Earth. The Street View gives you a good impression of the surrounding enviroment. I live pretty close to the lake Korttajarvi and the bridge doesn’t cross the lake, but the river running into it, and the lake is rigth next to a town of Jyvaskyla, population 130 000.

The cordinates of the lake are 62°20’16.10″E and 25°41’30.14″N (Google Earth).

1. I found the location on google earth but the views were not very good and I couldn’t really see anything that jumped out to me as an aha. Nor could I see the bridge. Nor the town you refer to, although others were called out. This could be my poor Google Earth ability, since I just downloaded it. Yahoo sattelite map not much better, though. Can you make your point more explicitly for what exactly I should look for.

2. I skimmed the midge thesis, you referred me to. can you please identify what parts of the thesis validate “the Tiljander thesis”? Page number? We are talking about two 70 page documents!

3. And does the midge thesis validate the bridge concern or Tiljander’s overall qualitiative comparison of her core to Roman Warm Period and such?

> 2. I skimmed the midge thesis, you referred me to. can you please identify what parts of the thesis validate “the Tiljander thesis”?

Thanks for the opportunity to clarify. I wrote,

It’s highly likely that Tiljander03′s overall interpretations of the Lake Korttajarvi data series as climate proxies pre-1720 are generally correct. Tiljander and her advisor and co-authors are the sole ‘local’ authorities; their views are consistent with other paleolimnologists’. E.g. … Tomi Luoto’s repeated citations of Tiljander03 in his 2010 dissertation [on fossil midges]…

p. 45, “The results of Tiljander et al. (2003) from the central part of the country [indicate that] the LIA was a wetter climatic episode in Finland.

These cites do not, of course, “validate Tiljander”–nor was that my claim. They address a narrower but still worthwhile question: how are Saarinen, Tiljander, Saarnisto, and Ojala viewed by relevant paleolimnologists? Are their views outliers; are their results discounted due to sloppiness, or unreliability, or a history of unfounded speculations? Here, we see Prof. Salonen of the University of Helsinki, apparently comfortable with his student Tomi Luoto citing Tiljander03 as an authority for characterizing the Little Ice Age (ca. 1550-1850) as being a variably colder, wetter period in southern Finland.

Are there opposing interpretations from these or other records that suggest something different, e.g. that contest Tiljander03 on climate regimes in southern Finland over the past centures? Judging from this sample, that does not seem to be the case.

> 3. And does the midge thesis validate the bridge concern or Tiljander’s overall qualitiative comparison of her core to Roman Warm Period and such?

No. I wasn’t anticipating such validation. Looking now, I don’t see any.

I just looked at Fig. 14 of TP Luoto’s dissertation on pg. 36; it includes a water temperature graph of Lake Hamptrask, Finland (just northeast of Helsinki) from about 1350 to the present. It’s inferred from fossil Chironomids. There’s a pretty clear dip where the Little Ice Age should be. From Fig. 5, Lake Hamptrask is about 270 km south of Lake Korttajarvi. At Bitbucket.org, I’ve uploaded a file that shows three Tiljander proxies (Darksum, Lightsum, XRD; 20-year averages, oriented per Tiljander03) and the Luoto proxy (image reversed and rotated from the dissertation).

The file is “TiljHamptrask.jpg”. You can get it by going to my directory (see earlier upload’s URL) and clicking. I’ll link it in a post following this one.

All three Tiljander proxies are contaminated post ~ 1750, but that still leaves ~400 years to compare with Luoto’s record.

To me, none of the Tiljander records seem to say much about climate changes (eg temperature or precipitation) going into the LIA.

Flipping Lightsum or XRD to make them match with Mann08 instead of Tiljander03 doesn’t help matters.

Of course this is a comparison of trends from places 270 km apart, one near the Gulf of Finland, but still. The LIA was supposed to be a widespread phenomenon.

More people should get into the habit of looking at primary data, especially when data-related questions arise.

> 1. Independence

Note that I plotted LS upside-down (heh) to follow Tiljander03’s convention; her “warmer” is towards the top of the graph. XRD as well.

> 2. Luoto

Agreed. We see a ‘clean’ proxy series and go, “aha.” (1) LIA, (2) No 19th/20th Century craziness, where the lakes hafta be hot tubs in the winter or ice-crusted in the summer (depending on which way you orient the graph).

Re: scientist (Aug 5 01:31),
Of course, the series are not independent, and there is really only one variable. That’s immediately clear from the Tiljander paper or the Mann SI. Only a fool would attempt to use these as four independent proxies.

Correction: LS and DS are correlated, not anti-correlated.
This means that the interpretation of Tiljander et al (DS=Temp, LS=-Temp) does not make much sense.
In a more recent finnish paper (see later post) LS, DS and thickness are all interpreted as -Temp.

My gut feel is they are not good for much also…or at least Tilj hasn’t really figured out a way to extract much of a story from them. she had a lot of comments about how her stuff compared to other papers in the RWP, but I got more the sense, she was reading those papres and then saying “oh…my series corresponds), than that she was really looking at the series, asking what to do they tell me on their own, pause, then compare and contrast to previous work.

HotBother, It would be a big help if you could list what you see as the major arguments, and identify the places where they have been answered and/or exposed as nonsense on realclimate.org. You can post links here, or in the comments here; I will add them to that compilation of relevant blog posts. Thanks.

Hot Bother:
Your comment is withut foundation.
I have been to RC. Gavin even responded to some of my comments. You certainly can learn some things though primarily from the posters. However, as you can see by reading carefully through the 561 comments on the Montford post to which the current post is a rebuttal, Gavin has declined to extend the discussion at RC and has not posted follow up comments from a number of substantive and polite commentaters here.

Hotbother: Gavin uses and abuses editorial power at RC. After watching the shameful, abusive, and unprofessional way that he treated Dr. Roger Pielke Sr when he posted there, I won’t even give them the benefit of my visit to their horrid little blog. They can wallow in their groupthink. Climateaudit is a much better venue – where even people like “Scientist” are engaged in conversation, rather than the textual smackdown you get at RC.

I have a confession to make. At the same time I posted the above I tried to post this on realclimate.org:

What a bunch of mugs you lot are – all your arguments have been answered and exposed as nonsense on climateaudit.org, but you will never go there to discover how wrong you are, will you? Signed Cool Cucumber

It didn’t get past the moderator. So I tried to post a more polite version on realclimate.org’s most recent thread. That didn’t get posted either. Then I wondered whether Cool Cucumber lacked enough substance to get posted, so I tried to post this:

From September 2008, Michael Mann maintained the argument that the erroneous use Dr Tiljander’s study didn’t matter because he could validate his Hockey Stick without it, and without tree rings. Then he had to surreptitiously conced that without Tiljander and tree rings he can’t validate the Hockey Stick earlier than 1500 AD, which means he can’t validate it at all. This back down was slipped into a rationalization in Mann et al 2009, and made more explicit by Gavin, followed by the ridiculous exculpation that “the exact level of medieval warmth is not a very interesting scientific question” anyway! So what about the widely publicized claims made in 2008 that a Hockey Stick could be validated without tree rings and even extended from 1000 to 1300 years? You people don’t want to talk about that any more? Or does that depend on your audience and how many awkward questions they ask and what you think you can get away with?

Your comments overnight display an unexpected and rapid uptick in familiarity with the proxy issues that have bedeviled paleoclimate reconstructions. This suggests that a certain amount of disingenuousness accompanied your earlier (truthful) declarations of ignorance on Tiljander-specific questions.

I would thus refer you to Richard Feynman’s Caltech address, famously known as “Cargo Cult Science.” If you want to live up to your self-chosen moniker, your job is not to market “your side’s” preferred sciencey product, but to strive for dispassionate examination of the facts, theories, and logical arguments that are under consideration. Why should McIntyre or Ianl8888 or I have to repeatedly point out things that you could have (and thus should have) spotted in your reading, and highlighted?

Here is a quote from the philosopher Emmanuel Goldstein that aptly describes the difficulties in discussing both the details and the significance of the use of the Tiljander proxies in Mann08. It will give you pause or cause you to roll your eyes. Whichever.

Crimestop means the faculty of stopping short, as though by instinct, at the threshold of any dangerous thought. It includes the power of not grasping analogies, of failing to perceive logical errors, of misunderstanding the simplest arguments if they are inimical to Ingsoc, and of being bored or repelled by any train of thought which is capable of leading in a heretical direction. Crimestop, in short, means protective stupidity.

Re: scientist (Aug 4 16:14),
scientist
I am enjoying your participation here, especially where you work through ideas and explore questions about Tiljander and calibration that may not have been considered here before. However of the last 15 posts listed, 11 are from you. Perhaps you could focus a bit more?

Sci, there have been a lot of very good threads here over the time I’ve been watching, but this is one of the very best. So often the discussions build to a point and then plateau in a circular dance which neither clarifies the divergences nor recognizes the areas of agreement.

Your persistence and the responsiveness, (it seems to me), of the people who have worked on this with you is wonderful.

thank you all.

Steve: For the most part, TCO has been on good behavior. It’s nice to see.

>>Your comments overnight display an unexpected and rapid uptick in familiarity with the proxy issues that have bedeviled paleoclimate reconstructions. This suggests that a certain amount of disingenuousness accompanied your earlier (truthful) declarations of ignorance on Tiljander-specific questions.<<

"This" doesn't suggest. You suggest. I've been upfront with my level of background, (saw some typical Steve disorganized posts back at the time, knew there was a big blogstorm, knew it would be a lot of effort to get to true understanding since the issues are not simple and (I've learned) not to take either side at face value, but to pressure test.) If you can't fit that into your meta-view of people, tough. I'm an odd duck. And in terms of evolution over the night, probably a combination of reading Boreas and googling Dean and the Swiss papers after you gave me the homework assignment. That and wikipedia. The insights about XRD and chemical composition and such are just me trying to grasp what is going on.

<>

Know it well. Done my time on the mesa, inside one of the two double fence buildings up there. The man was still remembered there. Had lunch with the guy who made the molds for the first devices…he said Dick was a cool guy. Bought all his books. But…I’d refer you to his Shuttle examination as the more exciting and relevant read. 🙂

<>

The funny thing that you and so many can’t grasp is that I’m on the denialist “side”. Relio trulio. But only if it’s right and if it’s fair.

<>

-because the previous explanations have not been well organized?
-because Steve is rehashing stuff and discussion is allowed?
-because it’s more interesting than ingroup gesture posts?
-because I end up raising interesting issues
-because if you don’t want to, just blow it off…

<>

Well, I must have crimestop or something, because my brain just turned off to read that. I must be too timid or something.

On reflection, the exchanges with ‘scientist’ yesterday on this thread serve to illustrate the bind that the authors of Mann08 have placed themselves in.

It’s highly likely that Tiljander03’s overall interpretations of the Lake Korttajarvi data series as climate proxies pre-1720 are generally correct. Tiljander and her advisor and co-authors are the sole ‘local’ authorities; their views are consistent with other paleolimnologists’. E.g. McIntyre’s cite of Atte Korhola, supra (#237675), Antti Ojala’s citations of Tiljander and Saarinen in his 2001 dissertation (linked by Jarmo #237548), Tomi Luoto’s repeated citations of Tiljander03 in his 2010 dissertation (linked by Jarkko #237696), Ianl8888’s remarks supra.

There are no qualified experts that have expressed contrary views, to my knowledge.

The first part of Mann08’s authors’ self-inflicted bind

If Tiljander and coworkers are correct: Mann08’s authors are wrong.

First, they are wrong because they ignored Tiljander03’s (and Tiljander05’s) warning that the Lake Korttajarvi data series would not be calibratable to a post-1720 climate record. Mann et al. thus calculated four nonsense correlations (Yule, 1926), one for each proxy, and proceeded with their paleotemperature reconstructions.

Second, they are trivially wrong because in calculating their nonsense correlations, they failed to notice that they had turned two of Tiljander’s data series upside-down, Lightsum and XRD.

Third, Mann and co-authors have undertaken a substantial violation of scientific ethics (viz: “Cargo Cult Science”) by failing to acknowledge and correct their mistakes, in their February 2009 PNAS Response to McIntyre and McKitrick, and again (implicitly) when uploading their first re-do of SF8a on their PSU website in late 2009, and again (implicitly) when uploading their second re-do of SF8a on their PSU website in early November 2009.

In addition, it seems fair to suggest that other climate scientists who knew better, or should have known better, have worked to enable Mann08’s authors, helping them to dig in deeper rather than searching for a way out.

The second part of Mann08’s authors’ self-inflicted bind

If Tiljander and coworkers are wrong: Mann08’s authors are wrong.

“Tiljander and coworkers wrong” must mean two things.

First, that their warning about post-1720 non-climate contamination of the varve record did not render their data series unusable in the 19th and 20th centuries, and thus related to the instrumental temperature record only by nonsense correlations.

Second, that Tiljander03’s pre-1720 assignment of the relationship of data series to temperature was correct for Darksum, but flat-out wrong for Lightsum and flat-out wrong for X-Ray Density. “Flat-out wrong” in these two cases means “upside-down”: Tiljander03 asserts that rising proxy values correlate to cooling temperature, while Mann08 claims that rising proxy values correlate to warming temperatures.

To my knowledge, there is no reason to think that this is the pathway that Mann08’s authors took to accomplish their paleotemperature reconstructions. But this is the line of reasoning that Mann08’s enablers consistently refer to. It is implicit in the “I don’t know, and it doesn’t matter” defense that has been proffered in Gavin Schmidt’s post at Collide-a-scape and by Martin Vermeers and others at Arthur Smith’s “Michael Mann’s errors” post.

So let’s explore it further.

If this is correct (again, I don’t think it plausible), then Mann08’s authors have engaged in a substantial breach of scientific ethics (viz: “Cargo Cult Science”) by citing and quoting Tiljander03 as an authority on the Lake Korttajarvi data series, while failing to note that their paper was departing completely from the cited interpretations. This would be highly misleading to PNAS’ editors, to peer reviewers, and to readers.

Secondly, one would have to ask about this part of Mann08’s bind: “What are the odds?”

In constructing their proxies for paleotemperature, these authors then accept the sole authority’s orientation (but not correlation) on Darksum, reject their orientation (and thus correlation) on Lightsum, reject their orientation (and thus correlation) on XRD, and invent a new correlation on Thickness.

And this process yields a skillful and validated reconstruction! Heck: Gavin Schmidt says that these proxies even extend the validation of the essential no-treering EIV reconstruction from 350 years to 850 years!

Wow! Talk About Lucky!

.

[This’ll hopefully be my swan song for this thread. I’ve other matters to attend to…]

Seems like some snark is allowed, some gesture posts (Kim limericks), some digressions. But more from your side than from the converse. I do realize that within-tribe silliness is less water-roiling (note the Tilj tie-in) than enemy-tribe silliness. But it’s still not fair.

It can be useful to visualize the Tiljander proxies, graphically. This JPEG file at BitBucket portrays 20-year averages for Darksum, Lightsum, and XRD (I don’t have Thickness to hand).

Notes: (1) All three proxies are oriented per Tiljander03, with “warmer” at the top and “cooler” at the bottom of each graph. (2) The gray box at the left of each graph denotes the period of progressively elevated non-climate contamination, as described in Tiljander03. (3) This dataset (from NOAA) runs from 0 to ~1987 (not all the way to 1995).

Nice picture. Random thoughts (lot of words and not that much killer insight):

1. Looks like pre-1700s, that there is a lot more relative variability of XRD than in LS or RS. Wonder why?

Actually reloooking at it, I think this is from the axes and driven by the differences in recent excursion. If we cut off the 1700+ part and then standardized each, they might be comparable.

2. I admit that XRD seems the more tractable and physically familiar measurement to me than LS or DS. Kind of am biased to using it.

3. Wonder what is driving the differences in XRD. Is it purely a matter of composition? Higher mineral fraction? Type of mineral? We sure that compaction has no effect? I suspect that some physical insights into what is driving the XRD results would help us with our problem. And just kinda cool to know what is going on physically regardless. I know she does some mag susceptibility and ashing. But maybe quantitative analysis of a few select microtomed sections would help. not the whole core. but some sampling. Just wonder if there is some clue we get from that.

4. I wonder if some sort of approach to exclude supervarves makes sense. Just to clean things up. Not sure if that happens when a pebble hits the core or when a tree falls in the river coming into the lake or a beaver dams the stream or when a fish dies and falls on the lake bottom. And of course, culling outliers is dangerous. But I just wonder if that kinda screening helps get us a more revealing series.

5. Are there no significant biological sources of inorganic material? Just wondered. Some of the other studies talk about diatom shells and the like. I have a simple model in my mind of chemically inorganic metal oxides and silicates being the spring melt DS part of the varve, and then chemically organic goo (fish poop or whatever) being the summer stuff that is LS.

6. Looking at the XRD, looks like there is a big plunge after 1100 and then a different regime from then to about 1700, followed maybe by another from 1800-1950 and then another plunge. Even if you leave aside the post 1700 period, not sure how you explain the phase change from 0-1100 versus 1100-1700 in terms of the typica story of Scandanavian climate. Somethings driving that series. Almost feel like I’m staring at a stock chart (and I hate technical analysis). Really land usage by the nearby population seems more the likely driver? I wonder what is driving the failry reasonable sized excursions at 20 year intervals as well. With a tree, would think all kinds of biologial counfounders could drive it. Would think that the self-averaging in 20 year buckets would eliminate year to to year nuggest from significance. poor resolution of the instrument ought to drive more average of signal. I could see the climat itself having some sort of variability on that timescale, but then the century and millenial scale story doesn’t seem to make sense.

7. Given that Tilj doesn’t really have any kind of clear climate story on it’s own, midge-man’s comments about “agreeing with Tilj” seem a little off (maybe budd-buddyish?). Your comment on disagreement is more interesting…

4, supervarve exclusion: I thought of that too, eg Le Chauvanet’s (sp?) criterion. But I suspect it gets ugly fast, esp. with the time-series/red-noise issues tossed in. To me, intuitively, this actually gets to the overconfident and naive approach that the field takes in general, given that most data series are very noisy, and that some probably don’t have any climate (temperature) signal at all. The subject cries out for interdisciplinary work, where the treering people sit at the feet of actual experts and learn, rather than preach.

7, Agree. My point in copy-and-pasting the cites stands–nobody is gainsaying Tiljander03. But the more I stare at her series, the less they look like temperature proxies, or even, more charitably, like temp-and-precip combo proxies. This is a pie in the face for Tiljander03’s interpretations. But before Mann08’s enablers break out the champagne, they should think it through. “Hooray, we didn’t use a genuine proxy upside-down, due to carelessness with modern contamination! Instead, we used a series that’s signal-free noise upside-down, due to carelessness with modern contamination! And it’s the unstated properties of this upside-down noise that extend the validation of our EIV reconstruction from 1500-1850 many additional centuries back!” Hmmm, not good.

7. Yeah, pretty much. What was exciting about Mike’s paper were the new data series, and the potential for sensitivity tests sans tree-rings. But the dendence on Tilj only (and the failure of CPS and needing EIV is a sign of this, I think) and then the physical problems with Tilj (which look worse than tree rings at this point, to me) make the whole thing pretty weak.

That isn’t to say that there isn’t something we couldn’t get out of varves in the future. There’s always hope with new things. But neither Mike’s aphysical math-hopper, nor the Finn’s handwaving and level of analysis are getting us there yet. I almost get the feeling, the poor grad students are faced with a really tricky problem and samples that don’t tell a story, and then just try to weave something out of it, to get done and get the union card. The sad thing is that I’m the type who actually thinks all the data collection, physical analysis and even failed correlations are intersting. And I totally respect publication of failed experiments (within reason, but there’s a way to do it that is additive to science). I know the Finns did some hard work and took a swing at a tough problem, but better almost just to publish data and say one doesn’t have a good physical interpretation.

Amac and Scientist,
Just wanted to post a note of thanks for your discussions. [And hopefully this note stays out of the main line of your conversation.] I’ve only been able to follow the discussion at a distance because I don’t have much of an appreciation for varves and their subtleties; but you’ve elucidated a lot of the material.

The Tiljander series is of course notorious. It seems that you have come to agreement that this is not a reliable temperature proxy, at least in the most recent three centuries. Please correct me if I have misinterpreted here.

I’m wondering if either of you have investigated any of the other component series. [Beyond Tiljander and Graybill, that is.] In particular, the ones with non-predetermined orientations, which would seem to be objectionable on theoretical grounds alone.

[Replying down here since the reply link is gone from the sub-thread up above]

Yes, I understand that weather patterns exist. What I do NOT understand is how weather thousands of km away can override weather conditions occurring at the same time locally.

If you have a weather pattern in one locale, that then moves on to another locale, that’s not a “teleconnection” (again, I haven’t seen a quantitative definition of the term), that’s local weather in one locale moving to another, and changing along the way. They do not occur simultaneously, though this is what Mann seems to be arguing.

Example: Tree core samples are taken of several species of trees at one location. Some of them display extreme growth spurts while others do not, even within the same species. Are you seriously saying that weather elsewhere may only affect SOME of the trees in a given locale and not others within the same sampling area? If so, RomanM is right, someone needs to come up with a plausible physical process that can describe this relationship, amd not just say “it could happen”.

If you are really a scientist, and I’m having my doubts, then you’d know this. I’m not a scientist by any stretch of the imagination, but I can still understand scientific principles. Without an hypothesis, or supporting theory, it’s purely speculation.

RomanM: The reply link is gone because it appears that WordPress will only nest up to a maximum10 times in a sequence of comments. If there was no limit, then you could end up with comments that have lines one word wide.

Steve: The topic of “teleconnections” doesn’t have anything to do with the no-Tilj impact. The issue here is a narrow one.

Re: Jeff Alberts (Aug 4 10:00), BTW, Steve Mc, how about a new Unthreaded? I had a hard time the other day trying to find it when it wasn’t on the recent posts list. I did eventually find it via the search function, but it’d be nice to have a direct link to it. Say on the Pages section of the left sidebar. The point of Unthreaded, after all, is to keep unnecessary posts off the regular threads.

RomanM: The reply link is gone because it appears that WordPress will only nest up to a maximum10 times in a sequence of comments. If there was no limit, then you could end up with comments that have lines one word wide.

I figured that’s what the issue was. Thanks for the clarification. But comments are still being placed out of order when they’re not a direct reply…

For anyone interested, it appears highly likely that ‘scientist’ is the same person that posted over at Jeff Id’s blog TAV under the name ‘TC’. This poster exhibits the same style of trying to appear knowledgeable and intimate (refer to Mann as ‘Mike’ LOL) of the players and issues while clearly not having the math/science skills necessary to understand the topic in detail. This is also why he/she will never post a link to any research, paper or anything else from his/her hand cause none exists.
Carry on.

Re: david_in_ct (Aug 4 10:43),
Yes, ‘scientist’ is the person who used to post here as TCO. Same style of writing with random words in CAPITALS. Same style of telling Steve what he ought to do. Same suffering from blogorrhea. For confirmation see the open thread at deepclimate.
Steve doesn’t seem to have noticed this, or has he?

It would be odd if Steve had not noticed. He is just uber-careful to stick to his knitting and is scrupulously honorable about running the show. Part is probably who he his, and part is probably to contrast this place with RC et al. It’s a great thing that he has done it this way though lord knows where he gets the patience. Probably comes from living in the mining world where reputation is critical given the number of charlatans running around.

Out of curiosity I searched information on the lake. It is located north of Jyväskylä, next to (south)of village of Puuppola. A very shallow lake, its has suffered from eutrophication that has continued for decades, due to increased nutrient load from farming and other human activities. Lake suffers from algae, lack of oxygen and increased sedimentation. E4, one of the main highways in Finland, runs across the stream that connects Lake Korttajärvi upstream to Lake Vähäjärvi.

Farming started seriously around 1600-1700. Small lakes were drained for farming, ditches were dug to drain wetlands and the surface of Lake Korttajärvi was lowered by locals, apparently to create more dry land for farming.http://www.gtk.fi/data/mps/321206.pdf

I can well understand why Mia Tiljander considered data from 1600 onwards useless.

Ah, it’s attack Tiljander personally time now I see. I find her analysis cogent and reasonable frankly, only someone with an axe to grind IMHO could dismiss it so cavalierly. You know, this does look an awful lot like the old TCO vis-a-vis tactics.

Scientist, rather than just slag the analysis, why not make an informed comment ? You’re commenting but not terribly informatively. Tiljander has provided a reasoned interpretation of the physical data in terms of a set of proposed physical processes operating at the site. That these can’t be carried through to the modern period does reduce our certainty, however her interpretations are buttressed by other external climatic observations from the general area, so they’re not unfounded. By contrast, the opposite interpretation used by Mann & Co for two of the series has absolutely zero support, or if there is physical evidence to support their interpretation, it hasn’t yet seen the light of day.

No other user of the proxies has even deigned to make an informed comment let alone actually study the physical evidence, presumably making their interpretation exponentially more “strained and non-additive”, no ? We may conclude that there are possible other scientific interpretations of the varve data, however we haven’t seen any, leaving us with Tiljander’s by default as at least the most probably correct.

You’ve stretched most of the way down to a conclusion, what’s to stop you making a plain statement along the lines that “on the face of the best evidence we have to date, Mann 2008’s use of the Tiljander proxies was wrong on at least 2 counts: first they cannot be adequately calibrated due to modern period contamination, and second because even if we allow the calibration at least two of the series were used in the opposite orientation to the most probable physical interpretation.”

You see shades of gray when it comes to Mann08’s uses of the Tiljander proxies. Here’s a thought experiment that could lead you to express your ideas more clearly.

Suppose that you and I are working together on a 1,800 year paleotemperature reconstruction. My job is to find candidate proxies, yours is to calibrate them to the instrumental record, 1850-1995.

This morning, I say,

“scientist, I’ve found a reference to four promising 3,000-year-long lakebed sediment records! But there is a big potential problem: the geologists who obtained and characterized the drill cores say that each of the four records has large-scale contamination from 1720 to the present.

“I know the sources of the non-climate signals: farming and peat-cutting in the lake’s drainage area, local road-building, an episode of bridge reconstruction in the 1960s, and eutrophication (there’s a small city beside the lake).

“The geologists’ paper says that non-climate influences on the records have grown over the past 280 years, but they don’t offer a quantitative estimate of how the contaminating signals compare to the climate signals. 50% as large? 200%? 1,000%? Who knows?

“scientist, inclusion of these proxies will make the paper! We really need them!

“Briefly explain to me in simple, non-technical terms how you think you might calibrate these four sediment data series to the instrumental temperature record, 1850-1995.”

Indirect and super-duper complex approaches are out: we know from the SI that Mann08’s authors didn’t use them.

Sadly, then, my response has to be, “It can’t be done.” That ends the thought experiment for me.

Likewise, it’s over if the answer is “I’ll just ignore the recent history of non-climate contamination.” (I was already aware of that method of producing nonsense correlations.)

For us to believe that Mann08’s authors might have a logically tenable defense for their choices with the Tiljander proxies, there must be an answer to this thought experiment.

AMac, it appears there is a lot of words being spilled over very little disagreement. It is clear he understands what you are saying, and his only disagreement is that it is possible and acceptable to use the proxies in an orientation opposite to Tiljanders.
I’m going to post my commentary on your summary at your site.

Thanks, MikeN. But a number of times on Tiljander, I’ve reached what seemed to be a shared, logical conclusion with a correspondent… only to discover that either I didn’t understand their words, or they didn’t understand mine. A lot of people have a really hard time grasping the notion that Mann08’s methods are in error. So I try to write very carefully on the topic… even at the risk of writing too much.

If scientist believes that it is possible and acceptable to use the (Lightsum and XRD) proxies in an orientation opposite to Tiljander03’s, I hope he addresses the thought experiment. I think the reasoning behind his approach would be informative. Because the key question remains, “How do you calibrate the proxies?”

The fundamental disconnect I see is: It seems as if there’s a deep-seated acceptance of the assumption that allows teleconnection. “It’s a valid proxy because our tests of correlation turn out well.” Which is nothing at all like the statement “It’s a valid proxy because we understand the factors involved through causality tests, I can provide a calibration and a calibration bias/error, and it tests well in an out-of-sample period.”

Mann avoids most of that by the reasonable argument “The original authors thought it was a proxy, I’m not an expert on their field, I added it to the pool of potentially useful proxies.”

Once you’ve followed the path “Well-correlated implies good proxy,” you’ve already made the assumption that’s fatal to the case. So the argument “That isn’t a good proxy because of reason X” is always trumped by the inherent assumption. “It was discovered by the proxy-finder, so it’s good.”

This can be seen in the way “correlation” and “calibration” are used near-interchangeably. And also, really, in the way Mann’s method relegates the vast majority of available proxies to insignificant weights. To the point that there hasn’t been a peep about the “lowest ten” proxies according to Mann in years. Given the paucity and skill of surface measurements even at the height of GHCN, the reasoning for discarding those proxies seems ever fainter as time passes.

This is an independent concern. You could have the same fear of nonsense correlation from a proxy with no damning remarks in the data collection paper. Steve has said, that this is not the thread for addressing that concept. Good to see him disaggregate.

I’m having a hard time following your thought experiment, including the part where you say I would do various things I wouldn’t do (push for different standards for something because it makes the paper), and then want to know what I say a while longer.

I think you could,

1. treat it like all the rest of the proxies, just plug it into the hopper (I mean if your method has a danger of spurious matches, well…that’s what it has…that’s an issue of the methodology. And there are some safeguards…maybe not as high as you want, but again, this is a separate argument.

2. Do as (1), but note the physicality concerns in the paper, highlight physicality caveats.

3. Try to fix it somehow. I would probably avoid that as I don’t know how you fix and it becomes a rathole to go down (in work) if you end up having to do that for every of 1200 proxies. That said, attempts to “fix” like maybe using the pre-bridge years for validation only, might be a method of getting the most signal from noise. Or you could go and do a bunch of work to go to the site and read varveology and get a co-author who understands the issue (or at least consult one) to determine if the confounding is more a 10% issue or a 100% one.

4. Just not use it. I do think, in this case, it’s important to be fair though. Not to bias your final result because of what makes skeptics happy. (For instance, convert it around and say the Tiljander sediments really drove a high MWP result…and was excluded for the unquantified bridge extents. Do you think everyone on the skeptics side would be happy? Buehler?

The extent that you decide which to do, depends on how much you know. If you know the issue the way in your example (and not clear to me that they did), then you need to do something in bucket 2-4 based on some sort of judgment process. I have a hard time answering how to do that. Ideally, you would have everything formalized, and apply it equally to all the series. For instance, saying you intend to use every series of such and such characteristic and then just follow that as a rule. Or if you are going screen things based on physicality (from reading the papers) formalize that.

Of course, Mann didn’t do any of the 4 options you state. He tried to do option 1 (or 2), but erred because he used the series upside down. There is nothing in his code that flips a proxy based on which way would pass testing in the calibration period. Nor did he in the paper, or at any time since, ever provide any reasoning to justify why Tiljander’s interpretation was wrong.

This is really quite simple- Mann screwed up. Your attempts to portray this as shades of gray is quite unpersuasive.

Absent a cogent argument to wave away the concerns of contamination, a cogent PHYSICAL argument, absent that you are NOT pressure testing Mann’s decision. A cogent pressure test would be this. We have a plausible physical reason to junk the proxy or truncate it. It’s at best questionable and at worst corrupt. If you decide to accept it, you are making a statistical decision with no estimatable probability of being right. Your CI becomes junk overwhelmed by the probability of being wrong about waving away concerns with no basis.

You can of course wave it away and argue that somebody may propose a physical explanation. or not

1. Yep, you can just take the data series and throw them into the proxyhopper. Mann08’s authors added a few cavils in the text about possible contamination of Tiljander, but besides that, this is what they did, it seems to me.

2. Highlighting physicality caveats, maybe that helps later if something goes wrong, but what else is it good for? OK, four points awarded for honesty, but minus two for not doing a simple follow-up. As soon as you graph the three series, it jumps out that there’s obviously something very fishy going on with each one, late 1700s on.

One alone or One & Two together are going to lead to a spurious correlation. So that’s what happened.

3. Try to fix it somehow. Well we know Mann08 didn’t. If you’re stuck with using a direct approach (cf. splicing), it can’t be done, as far as I can see.

4. Just not use it. Yep. What you go on to say about “making skeptics happy” is wrong. The need is for predefined selection criteria. The subject is not simple with respect to either practicality or statistics. People in other fields think a great deal about these topics, and develop and revise procedures. Climate scientists, not so much. Their ability to learn useful methodologies from other disciplines, not shown to be high, at this point.

I’ve now read Tiljander. Scientist‘s rather disparaging remarks alerted me to pay attention to it. Attention was well rewarded. Tiljander refers far too much (by Mannian standards) to evidence for the MWP – supported by other local evidence in other papers, moreover. Look at this quote

Evidence of warming on the Kola Peninsula (c. AD 1000–1300) is provided by treeline studies, which show that pine grew at least 100–140 m above the modern limit during the Medieval period, which corresponds to a (summer or annual average) temperature at least 0.8°C higher than today (Hiller et al. 2001). A pollen reconstruction from northern Finland suggests that the July mean temperature was c. 0.8°C warmer than today during the Medieval Climate Anomaly (Seppa 2001). A study based on oak barrels, which were used to pay taxes in AD 1250–1300, indicates that oak forests grew 150 km north of their present distribution in SW Finland and this latitudinal extension implies a summer temperature 1–2°C higher than today (Hulden 2001).

The progress of this thread reminds me fairly strongly of some earlier threads with new visitors here who took up a lot of space and attention, until I (and I suspect others) ended up more confused than when I started. One newcomer, I forget his name, was given his own thread (eventually) and that worked nicely.

When I first read the paper, perhaps it was due to having already heard of Korhola’s comments, but my impression is that Tiljander just doesn’t believe in the hockey stick. She is aware that all papers have to acknowledge it, but then adds in lots of other references that go against it.

I wonder to what extent you are convinced of Tiljander’s hypothesis for what the series mean? Given she did not validate them versus temps. Given other papers (just from me googling last night) talk about precip proxies. Are you sure that colder winters have more snowfall and a more dramatic melt (seems reasonable but would you say this applies everywhere?) Would you bet your life on it? Would you be so trusting of her, if the story went the other way?

No I wouldn’t be trusting if it went the other way, whatever that means. I would be very critical if Craig Loehle then wrote a rebuttal reconstruction, turned the series upside-down, and then gave no explanation as to why they have flipped the series.

It’s not so much the total winter precipitation as winter temperature that is important. As a matter of fact cold winters usually have less total precipitation. However during mild winters most of the snow melts fairly quickly and there is not much snow buildup and little flooding in spring. In colder winters the snow accumulates and you get a strong spring flood. I live a few hundred miles south-west of Korttajärvi and here we are in a zone where there is little snow accumulation in most winters. However during the very slightly colder 1960’s and 70’s there was heavy snow cover and strong spring floods almost every year.
In the Korttajärvi area there is heavy snow accumulation in most winters at the current temperatures but a rise of half a degree or one degree would change the snow regime to periodic melts during the winter. It is this phenomenon that is the reasoning behind Tiljander’s hypothesis that strong spring floods with heavy erosion and deposition in the lake is a proxy for winters that are similar to or colder than the present, while absence of spring floods is a proxy for milder winters, and based on half a century of experience of scandinavian climate I find it highly persuasive.

In the last couple of days I have put up a few posts at RealClimate to suggest that a common public forum would serve a useful purpose in the climate debate. No takers there, at least so far. I’m not naive enough to think that an outsider with no standing is going to waltz in and create a happy ending, but I wanted to put the idea on the record.

realclimate has had a practice of not merely not engaging with critics, but censoring them and, as much as possible, not acknowledging them. In the past, they’ve posted criticisms of me and refused to allow me to post a reply. In the points at hand, there’s no upside for them in engagement since the issues are unwinnable for them.

scientist, you present yourself as an inquisitive thinker with an open mind, but your actions do not support that avatar.

Your reply to RomanM’s statistical model explanation (7:53 AM) and subsequent posts seemed to me to indicate that you did not agree with/understand much of what he said. You did not reply to the essense of his points, and instead attacked some strawmen.

He didn’t scoff at teleconnections as you suggested in your reply. He stated very clear and simple requirements for including that type of factor in an underlying statistical model. Do you agree or disagree with those requirements? If you agree, can you point to where Mann met them, even partially? I’d like to know your thoughts on those topics, but I’ve got to tell you, your reply just made no sense.

For another example, your subsequent posts suggesting defects in or alternatives to Tiljander’s analysis coupled with your defense of Mann “I don’t know. Maybe Mann is really pulling signal out of noise with his mining methods. I don’t have the stats background really to …” is quite a contrast.

Tiljander provided suggested meaning to her observations, based on a proposed physical model. She made no attempt to relate her work to recent temperatures, due to on-site observations and information, included as part of her work.

Mann pretty much did the opposite. He attempted to relate her work to recent temperatures (effectively discounting the only published authority, Tiljander, without comment or explanation). He then assigned meaning to her observations that directly contradicted the only published authority for at least some of her observations, again without comment or explanation. And he made no effort at all to connect this to a physical model, much less a statistical one.

In this instance, Tiljander is careful and measured (I’m not asserting she is correct, just that she is careful). Mann on the other hand is careless, and unscientific (or at least incomplete) in his use of statistics with no foundation. Yet you criticize Tiljander and defend Mann. A remarkable response to these contrasting actions for one with an open mind.

RomanM was responding to me. I had clearly said I was not debating the quality of the model but clarifying the concept of one thing correlating to another. then Roman chose to debate the quality of the model. then I told him I was not debating the quality of the model, but clarifying the concept. Then you said, I was not addressing RomanM’s debating the model. Then I wrote this comment.

For those having difficulty understanding how meaningless correlations can arise in real data, here is a question from one of my Intro Stats exams:

The graph below shows the scatter-plot and regression line where the response variable y is the annual trade balance (exports – imports) of the U.S. (in millions of dollars) and the explanatory variable x is the annual number of injuries in boating accidents.

The regression equation is

U.S. Trade Balance = -2,000,000 + 486.32 x Number of Injuries

and the correlation coefficient is 0.941. The annual boating injuries thus explains 89% of the variation in the annual U.S. trade balance. Which one of the following statements is appropriate?

(a) The presence of an outlier is the main problem with applying regression analysis to these data.

(b) U.S. trade balance would improve if more people got hurt in boating accidents.

(c) Cheap Chinese imports are making boating safer.

(d) This is a case of spurious correlation.

It was amazing to watch, year after year, how many students could not come to terms with the fact that (d) is the correct answer.

More injuries in the U.S. cannot increase the labor force utilization in the U.S. Therefore, domestic production cannot increase as a result of more injuries. Exports come out of domestic production, therefore, they cannot increase. The slope of the import function is between 0 and 1. Therefore, lower domestic production cannot result in higher imports either.

So, we have a situation where both exports and imports are expected to decline with more injuries. The change in exports - imports then depends on which one declines more as a result of more injuries.

So, (b) has the appearance of plausibility. However, note that this equation does not control for any other variables, so that chain of argument is void.

Variables on both sides of the equation are related to an omitted variable: National income.

Steve, I don’t want this subthread to get out of hand, so please snip if necessary.

@Sonicfrog: But, total imports cannot increase, as I explained.

However, the students in my Intro Stats class did not need to know economics to know that (b) is not the most appropriate answer: Just look at the magnitudes.

The slope term tells you that one more boating injury will improve the trade balance by a whopping $486 million.

Trying to theorize about why the regression equation (and the spurious sample correlation) makes sense is not a fruitful exercise. It is far better to realize spurious sample correlation for what it is.

#92 There are so many false premises and misunderstanding in your ‘logic’ that I don’t even know where to start. I’ll start off with by pointing out that I was just reading the papers concerned and reported what they said – there was nothing new to my comments at all. If other people had not read those papers, that is not my fault…

So, we have reasonable constraints that suggest the feedbacks are net positive (amplifying), observations/theory/models that explain the bulk of that effect and remaining uncertainties on one (key) part of it. But if you want to claim that the clouds can cancel out everything else, you still need to explain why the planet appears to be so sensitive to changes in the past. No-one has successfully done so. Not even close.

In 116 he says this:

But your main question is whether or not the overall medieval temperature is ‘interesting’? Obviously many people find many different things interesting, and so what is not interesting to me may be fascinating to someone else. So let me define terms. I consider something interesting (in this context) if it allows us to better constrain possible future climate change. Other people may be interested in the medieval period for its own sake, but I am very much focused on using paleo-climate information as best we can to inform future predictions (see Schmidt (2010) for a clearer explanation of this).

He doesn’t even see the contradiction there. I’m tempted to post this question: “Gavin, in light of the two responses I’ve quoted, how far back in paleoclimate record do you think is relevant to your work?”

Perhaps my #127 on Tiljander will elicit a response. I think Gavin is trying hard to step away from the potted responses. If so, that’s admirable, and could be a step towards a thaw. It’d be great if Keith Kloor ends up taking a bow for fostering that sort of sea-change.

I have followed the web discussions for a long time now – but I think this is my first post.
I am quite sure now that Gavin (and others) considers the question of accurate paleoclimate reconstructions as complete distractions. They are happy to put out authoritative statements about them, but they have no real attachment to the issue itself.

This is his most recent comment on Collide-a-scape Blog on the post which was an interview with him:
“Furthermore, your question appears to imply that you think that our concern about future climate change is related to the changes we have seen already. That is not the case at all. Temperature changes so far have been modest and for the most part people and ecosystems have adapted to changes (though for some that has not been cost free). Rather, the concern is related to the fact that we can easily foresee further changes, driven in large part by the continually increasing CO2 level, that completely dwarf what we have seen so far, and complete obliterate the idea that medieval times would be at all relevant. A 3ºC change by 2100 – which is not the high end projection – puts the planet in a temperature range not seen since the Pliocene some 3 million years ago. A period of radically different climate and sea levels some 20 meters above today. That is what people are worried about.”

Other comments from him indicate that his view of the whole question revolves almost entirely around the “physics of the greenhouse effect” and very little from historic reconstructions – apart from the end points as per the above.
For example this: “The reason why climate policy is an issue because greenhouse gases are increasing in the atmosphere due to human activities at a very rapid rate. We know how the greenhouse effect works, and we have evidence that climate sensitivity to increasing GHGs is significant. It has nothing to do with whether it is warming now, or whether it was warmer at some earlier point (both of which are true though). Detection and attribution of climate change in the 20th Century gives us some confidence that we know what we are talking about, as do model-data comparisons for paleo-climate. But as President Johnson said in 1965, Wally Broecker stressed in 1975, and Charney illuminated in 1979, increasing emissions are going to cause problems. And note that was before the warming of the last 30 years. Feel free to ignore any paleo-climate data if you want, but it doesn’t affect decisions about risk management going forward.”

How much is Gavin driven by the physics and not the history? Well, at another place he says his preference is “a) I’d like to see a price on carbon emissions – by whatever method can be made to work. – without this there will not be enough market pressure to reduce emissions before we are committed to living on a different planet”.

So when he gets annoyed when people are finicky about the data or processes used – we need to realise that he really believes we will soon need to vacate the planet because of our emissions. When this is the mindset behind the “consensus”, then it leaves very little room for quiet discussion or reasoning. One wonders what it does to the “science” as well, since now is the time for action, not discussion.

Well, it may be as you surmise,, but the fact remains they have defended the reconstructions vociferouslly and violently ever since Steve and Ross wrote their first paper some years ago. And Soon before that. Now it appears that at least Gavin has realized they cannot be defended any longer (wonder what he is telling Mann), “So, well, shoot, they really don’t matter anyway. Avert your eyes for a minute: we are just gong to jump off that old, wore-out horse and ride this here one;” which, I assume, are their models. The next audit ground?

In my comments to AR4, I suggested that, if the paleo reconstructions don’t “matter”, the topic should be removed from AR4 with a short notice to Policy=makers that since AR3, it had been decided that the topic didn’t matter after all.

In my comments to AR4, I suggested that, if the paleo reconstructions don’t “matter”, the topic should be removed from AR4 with a short notice to Policy=makers that since AR3, it had been decided that the topic didn’t matter after all.

Let’s note that the EPA’s staff of lawyers maintain a very keen interest in the paleoclimate temperature reconstructions; in the specific conclusions of MBH et al; and more generally, in the arguments being made against the existence of a truly worldwide Medievel Warm Period — representative examples of which appear on RealClimate on a regular basis, and more importantly, in the IPCC documents EPA relies upon as their scientific basis of reference.

After all, even the EPA’s own lawyers, non-scientist professional bureaucratic infighters that they are, seem to recognize that if Mother Nature could, in pre-industrial times, raise the earth’s global mean temperature to levels approaching today’s levels — but without the benefit of having that additional 100 ppm of atmospheric CO2 with which to force the increase — then key parts of current AGW theory can be called into question, even the climate prediction models. (And, if one really thinks about it, perhaps most especially the climate prediction models.)

As evidenced in their recent rejection of the various reconsideration petitions filed against the EPA CO2 endangerment finding, both the topical content and the choice of wording that the EPA’s lawyers employ in the explaining their rejection decision appear to be something Gavin himself could have written over on Realclimate — and at various times over the last several years, probably did.

It’s not just the paleo reconstructions that Gavin seems to have given up on. I was staggered when I saw what Gavin was saying with regards to temperatures. Because it’s not just paleo temps that suddenly don’t matter to him, it is current temps too. Quote: “We know how the greenhouse effect works, and we have evidence that climate sensitivity to increasing GHGs is significant. It has nothing to do with whether it is warming now, or whether it was warmer at some earlier point.”

I find that disturbing. I’ve posted another message on that thread asking him if there are ANY possible observations that might change his views on the theory of global warming.

Re: Brian Eglinton (Aug 5 07:59), Chapter 9 of WG1 is about attributing climate change. Without the reconstructions as valid, the summary quoted partially below does not make sense. As written, I do not think the consensus can back away from paleo-work and maintain their claim of confidence. http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter9.pdf
The widespread change detected in temperature observations
of the surface (Sections 9.4.1, 9.4.2, 9.4.3), free atmosphere
(Section 9.4.4) and ocean (Section 9.5.1), together with
consistent evidence of change in other parts of the climate
system (Section 9.5), strengthens the conclusion that greenhouse
gas forcing is the dominant cause of warming during the past
several decades. This combined evidence, which is summarised
in Table 9.4, is substantially stronger than the evidence that is
available from observed changes in global surface temperature
alone (Figure 3.6).
The evidence from surface temperature observations is
strong: The observed warming is highly significant relative to
estimates of internal climate variability which, while obtained
from models, are consistent with estimates obtained from
both instrumental data and palaeoclimate reconstructions. It
is extremely unlikely (<5%) that recent global warming is due
to internal variability alone such as might arise from El Niño
(Section 9.4.1). The widespread nature of the warming (Figures
3.9 and 9.6) reduces the possibility that the warming could have
resulted from internal variability. No known mode of internal
variability leads to such widespread, near universal warming
as has been observed in the past few decades. Although modes
of internal variability such as El Niño can lead to global
average warming for limited periods of time, such warming is
regionally variable, with some areas of cooling (Figures 3.27
and 3.28). In addition, palaeoclimatic evidence indicates that El
Niño variability during the 20th century is not unusual relative
to earlier periods (Section 9.3.3.2; Chapter 6). Palaeoclimatic
evidence suggests that such a widespread warming has not been
observed in the NH in at least the past 1.3 kyr (Osborn and
Briffa, 2006), further strengthening the evidence that the recent
warming is not due to natural internal variability.Moreover, the
response to anthropogenic forcing is detectable on all continents
individually except Antarctica, and in some sub-continental
regions. Climate models only reproduce the observed 20th century
global mean surface warming when both anthropogenic
and natural forcings are included (Figure 9.5). No model that
has used natural forcing only has reproduced the observed
global mean warming trend or the continental mean warming
trends in all individual continents (except Antarctica) over
the second half of the 20th century. Detection and attribution
of external influences on 20th-century and palaeoclimatic
reconstructions, from both natural and anthropogenic sources
(Figure 9.4 and Table 9.4), further strengthens the conclusion
that the observed changes are very unusual relative to internal
climate variability.

The data from this paper (as well as Tiljander) was originally used upside down by Kaufmann et al (2009), see Steves post on the Kaufmann Corrigendum. In the Kaufman SI update correction they say “Record 21 was corrected to reflect the interpretation of Haltia-Hovi et al. (S33) that varve thickness is related inversely to temperature” (it is amazing that Mann continues to deny this after Kaufmann et al have acknowledged it).

This paper has some advantages over the earlier Tiljander et al one. There were 8 cores (rather than 2) and there is less of an issue with recent human interference (more remote area). The 8 cores show a consistent picture. They say that thickness and DS are very highly correlated (r=.99) and it looks like LS is also positively correlated with these. They interpret these as being inversely correlated with temperature. I think the argument is partly that when the lake is frozen over, stuff settles out more easily.
They say MWP and LIA are ‘subtly recorded’ by the varves.

Far and away the most lively and interesting discussion I have yet seen on Climate Audit The whole subject of temperature proxies is clearly fraught with numerous hazards and very far from being a settled branch of science.
I am left feeling immense sadness at the lack of willingness to engage in a proper team effort. The whole discussion still seems locked in a for and against AGW mode.
The negative reaction of Mann, Jones et all to Steve’s initial critique of the hockey stick graph was utterly uncalled for and his statistical prowess is a valuable asset which should have been capitalized on rather than rejected.
A better understanding of the validity or lack of validity of temperature proxies will remain elusive and quite literally confusing unless and until climate science comes to be treated in a proper scientific manner with complete openness and a healthy interchange of data and ideas.

Gavin makes 5 dot points to detail the handling of the Tiljander proxies.

In short
– lake sediments may contain climate related signals – in the case of Tiljander there were known issues,
– Mann et al (2008) used these proxies. In CPS method, local correlation fixes the orientation. If you have reason to believe this is wrong the proxy should not be used.
I will quote 3) in full:
“3) Since Mann et al (2008) were very aware of the potentially dubious nature of the modern portion of the Tiljander proxies, they performed their reconstructions without those proxies (and three others with potential problems) in sensitivity tests in the supplemental information (specifically Fig S8). Neither reconstruction (for NH mean (EIV) or NH land (CPS) temperature) is materially affected by the absence of the Tiljander proxies. This is the identical result to what you would have if you had a priori insisted on the opposite orientation of the proxies in CPS.
– the validation using tree rings but not Tiljander go back to 700AD (EIV method) and 400AD (CPS method)
– if people object to using Tiljander or think they are upside down – the non-Tiljander reconstructions in the SI shows it makes little difference.
– “Nothing stated in the RC posts or comments was incorrect.” Without trees & Tiljander, “these methodologies don’t allow you to say anything before 1500.”… “All validated reconstructions show late 20th Century warmth as anomalous over the their range of validity.”

By which we can say that if we reject trees & Tiljander, we have confidence the temperature has risen in the last 500 years. I think this is my take home line from all this. The historical, large scale phenomenon supporting a MWP have not been addressed by these particular proxy studies.

His final line is: “(Consequences of all this)/(amount of time devoted to discussing it in the blogosphere) = a very small number.”
Which brings us back to the fact that this issue is considered noise and interference amongst the more important matters they are dealing with.

I am curious that he is implying that all the info and reservations about the proxies were always out there so there should never have been any fuss made about it.

2- Tiljander warned about post-1720 contamination in the Tiljander proxies.

3- Mann08 considered the warnings, then went ahead and used the proxies.

4- The 19th and 20th Century contamination was really bad, as a glance at a figure will show.

5- The correlations that Mann08 thought they found between 1850-1995 temperature and proxy signals were actually spurious correlations to contaminating non-climate signals.

6- The mistake itself isn’t such a big deal, it’s the refusal to fix the problem that’s the issue.

.

Gavin’s points are, um, lawyerly.

1- Varve records often contain climate signal, but they can be contaminated.

2- The Tiljander proxies were 4 out of 1209 proxies used. CPS correlates proxies to local temperature, fixing their orientation. EIV does not.

3- Mann was very aware of the potentially dubious nature of the modern portion of the Tiljander proxies. So he did sensitivity tests without them as Fig. S8. Fig S8 showed that neither CPS nor EIV is materially affected by including the Tiljander proxies.

3.1- Without Tiljander, CPS validates back to 400 and EIV validates back to 700.

4- Regarding Tiljander, Mann08 already showed all there is to show. There is nothing left to do.

5- All RC statements on Tiljander are correct. If you use neither Tiljander nor tree rings, reconstructions are valid back to 1500 for CPS and as far back as is stated in Mann09’s SI for EIV. All validated reconstructions agree that the 20th Century is anomalously warm.

.

At “The Main Hindrance to Dialog (and Detente)”, Lucia famously noted Gavin’s pronounced tendency to answer questions regarding Tiljander… but to not answer the questions that were actually being asked. Of my six points:

It’s not clear to me that Mann or Gavin concede the contamination of the Tiljander sediments. Also, when you say “absolutely”, I would say “probably” contaminated. I mean, I haven’t seen chemical analysis to prove contamination. I don’t think we know what chemical substance is in the sediments to give the dramatic LS/DS/XRD modern changes. Not: I’m not arguing that it’s a good proxy. Even a 50% good proxy. Just that it’s an overstatement to say it is 2 plus 2 = 4 contaminated, “absolutely”. I personally don’t know what the heck is going on with those sediments in either old or modern times. I take the info from Tilj as a very serious concern…but then I’m also not blown away by her thoughtfullness or consistency in the paper. Like I still have a bunch of questions on densification (need to look at thichness values…could all this just be a lack of compression for recent varves?) There’s some kind of long term trend from 1700 to present in that data and it’s probably land usage, but I couldn’t say it’s definitely land usage in the way I could say that Lance Armstrong definitely used EPO in 1999 since he had 6 old samples dug out and tested and they came back positive.

I think that the bigger concern is that the Mannian methods seem to grab anything with a recent ramp in the 20th century and then that basically passes validation (CPS) or gives a good correlation and places into the recon (EIV).* I’m not enough of a statistician to explain what worries me…but it’s something that Zorita would call matching a single degree of freedom (two trends). I don’t really know if the r value handles this, but what I would want is some “wiggle matching”. Like if we detrended each series over the period, would the proxy match the gyrations of temperature? When I look at Cobb’s coral poster and the temperature and the coral, you can pretty clearly see that the coral is “wiggle matching”. Not perfectly, of course, but you can see more than just a match of the long period trend, see some wiggles get matched. I think that Mike does a lot of just matching long trends, so when you get mean on him for the Tiljander, well, he’s all like “that’s how I usually roll”.

The whole “failure” to admit doesn’t bug me as much as the rest of you, since I don’t think Mike concedes the logic/science as simply as the picture of Amac. What bugs ME is that he wrote that PNAS paper with all the Tiljander stuff (quotes from the paper and all) in the SI. That stuff should have been been in the main paper. Essentially what made the new paper was having more series. But a lot of those new series were questionable (as shown by the quotes). that should have been front and center. And then publish in a more serious, specialized, lower level journal. Not the PNAS ego trip.

> It’s not clear to me that Mann or Gavin concede the contamination of the Tiljander sediments.

No, they clearly don’t. In my opinion, they aren’t playing by the rules of Science, but by the rules of PostModernScience. The First Rule of PMS is, “there’s no such thing as PMS, we are all upstanding traditional Scientists, and I’m offended that you suggest otherwise!” The second rule is, all the methods of scientific inquiry can be used, as long as they lead to the desired result. If they don’t, all the methods of rhetoric and forensics can also be employed, by our side only.

As an example of PMS at work, we have constructions about proxy validity like “I don’t know, and it doesn’t matter.” Even a seemingly simple notion like “I don’t know” takes effort to pin down. “It doesn’t matter” hardly needs its own link at this point. Then there is the logic that goes “maybe X, maybe Y. If X then A; if Y then B, so we must go forward weighing both A and B at the same time” (e.g. this subthread). This PMS strategy abandons the reductionist approach; arguments become so complex and confusing that… uh, scientist, what were you saying, again?

> Also, when you say “absolutely”, I would say “probably” contaminated.

Either the proxies are “sufficiently uncontaminated to enable a calibration to the temperature signal to be performed, 1850-1995,” or they are “too contaminated to be calibratable.” Now look at the graphs again. Let’s pick Lightsum, the series that more or less means “accumulation of mineral.” You think the 1850-1995 signal has temperature information in it? Really? Really? OK, let’s go back a few centuries and ask Excel for the mean and standard deviation; forget red noise and all that–very simple first-order approximation.

So you, Gavin, Mia, and I agree that from prior to the 15th Century through ~1720, Lightsum might — might! — contain a temperature signal.

Mia and I look at those 19th and 20th Century numbers and say, “Yikes! Those numbers are huge and variable! And they are huge and variable in a way that they just weren’t, in the 15th, 16th, 17th, even the 18th Centuries! Whatever temperature signal is in there, it’s overwhelmed by a deluge of contamination!”

Gavin looks at those numbers and says, “Hmmm, ‘possible anthropogenic contamination’ in more recent centuries, so ‘potentially useful, but also potentially dubious’. Let’s use ’em and see what happens!”

And you’re going with Gavin on this, because, despite these ugly numbers, despite the graph that’s level for centuries before going hyperbolic in the 20th Century, despite the obvious impossibility of meaningful calibration 1850-1995, despite the chapter-and-verse of roadbuilding, peat cutting, farming, bridge reconstruction, and eutrophication — I used the word “absolutely.” Without a clear-cut chemical signature for this hypothesized, so-called “contamination.”

> but then I’m also not blown away by her thoughtfullness or consistency in the paper.

OK, you convinced me of that. Now I wonder whether Lightsum and the rest are any sort of temperature proxy at all, because maybe Tiljander et al were scraping the bottom of the interpretation barrel. Um, that’s not an endorsement of Gavin’s position! Having a reconstruction whose validty is improved by adding upside-down (with respect to Tiljander03) noise isn’t better than having that validity bulked up by reliance on upside-down (with respect to Tiljander03) signal…

Are you sure you don’t want to change your vote?

> I think that the bigger concern is that the Mannian methods seem to grab anything with a recent ramp in the 20th century and then that basically passes validation (CPS) or gives a good correlation and places into the recon (EIV).

Well that is something of a problem, and I can think of four or so examples offhand.

> what I would want is some “wiggle matching”.

Agree, especially now that we’ve seen some.

> The whole “failure” to admit doesn’t bug me as much as the rest of you, since I don’t think Mike concedes the logic/science as simply as the picture of Amac.

I understand that Prof. Mann doesn’t concede anything to my view. That explains his conduct, but it hardly justifies anybody else’s. If he decides that the moon is made of green cheese and Apollo 11 be damned, will PNAS’ editors send that paper out to peer review, and publish it? Will Gavin then declaim, “I don’t know, and it doesn’t matter”?

I agree the graph looks ugly, with that recent rise. That concerns more than the big spikes. Gotta think something is going on there, but not sure what. My hypotheses are landuse or (lack of) consolidation. When you add the appearance of the huge ramp, and then the things in the text about the contamination, it’s a dubious proxy. I think in terms of the recent Zorita paper, that an expert would likely leave it out. I donno…a lot of these time series look pretty ugly. Maybe they’re used to that, from that.

Still…I would not say absolutely contaminated. EVen if you feel the concerns are high enough to warrent keeping the series out (and that would be my bet, right now), I would not overstate the case. I think given that we don’t know what the heck is going on with that series physically-chemically, we should not say things like it is absolutely contaminated. I would reserve “absolute” for where we have a higher junderstanding of the proxy, physically.

I don’t think getting angry about it is the way to go. Making a comment or writing up the methodological issue is better. I have no doubt the thing got through peer review without anyone worrying about Tiljander. It’s a long paper. That stuff was burried in the SI. I think the review was fine. The way to handle is not get angry at people not going along, but to present the issue. And have a little sympathy with journals or the like that see it as a dry methodology dispute.

And don’t get too angry when Mike replies that it doesn’t matter. 🙂

Actually a better thing would be to quantify the impact mathematically. Basically done now in the SI of Mann09, no? But in general, McI has way, way, way too bad of a habit of writing silly posts about the rain in Spain and getting people hot and bothered…and then Mike points out, “low impact”.

If the review had any use, it was “fine” as a concrete demonstration of the limits of the peer review process. Certainly not as any kind of post-hoc mitigation for employing Tiljander from convenience in the first place.

“Qui tacet consentit” does not wash in this instance.

The last paragraph in your reply serves to demonstrate an ignorance of the vast body of posts on this site, in both primary dimensions of tone and content.

I don’t conflate ignorance with stupidity, we are all extraordinarily ignorant from most perspectives.

> I agree the graph looks ugly… My hypotheses are landuse or (lack of) consolidation… it’s a dubious proxy… I would not say absolutely contaminated… I would not overstate the case… we don’t know what the heck is going on with that series physically-chemically, we should not say things like it is absolutely contaminated. I would reserve “absolute” for where we have a higher junderstanding of the proxy, physically.

I agree narrowly but not broadly with your general thrust here. You’re being nice, and it’s nice to be nice, but we also have to remember that guy Feynman, who was eccentrically charming but didn’t approach technical issues in terms of the importance of beeing agreeable with our scientific betters.

You’d have the basis for making a reasoned argument if Mann08’s authors and champions would offer some justification for the idea that Lightsum (to stick with that example) is a plausible temperature proxy. Then we could go back and forth, a “preponderance of the evidence” discussion. But Prof. Mann ducks the question, preferring to describe the fossil fuel lobby’s anti-Mann conspiracy; listen to Chris Mooney’s painfully fawning podcast interview if you’re feeling cruel (link at my blog). Co-authors, “Maintaining radio silence, sir!” When Gavin pronounces, how much prep work does he have to put into those legalistic turns of phrase and lawyerly grammatical ambiguities, do you think? Mann08’s other defenders are flyweights on this issue (name one who isn’t?).

So please take “absolutely” as my shorthand for “overwhelming evidence at this point that post-1720 Lighsum is invalid as a proxy for temperature, with no plausible rationale on offer that post-1720 Lightsum might be an acceptable temperature proxy (although new theories and evidence might change this picture).”

Saying you don’t like “absolutely” doesn’t cut it. You have to (1) Dispute the multiple lines of reasoning that each show Lightsumm to be an unacceptable temperature proxy (er, you’ve added to the pileup!), or (2) Propose a hypothesis by which Lightsum is (or might be) an acceptable temp proxy. Remember, the big piece of gristle here is that for Mann08, “acceptable” means “directly calibratable to the 1850-1995 CRUTEM3v record.”

> the thing got through peer review without anyone worrying about Tiljander… I think the review was fine.

I’d be interested in seeing the peer reviews and editors’ comments on Mann08. I have a pretty clear suspicion as to what they looked like, and it doesn’t map to yours. This was a shallow, perfunctory review process, “Yeah, looks good to me, my buddy Mikethe eminent Dr. Mann has once again contributed a brilliantly important synthesis. ‘Korttajärvi’ is misspelled as ‘Korttajarvi’ on page 6; this must be corrected.”

1. I have a comment in moderation addressing the PMS issue and Mann reluctance to engage on substance.

2. I like your little math analyis on the variability changes over time. It puts what bothers about the big ramp into words. That said, should that be a formal screening mechanism? Can it be defended as such? Even if so, it’s not 2 plus 2 simple. We just need to be real careful that we are not harsh on BCPs and

3. I’m not so much trying to get you to be nice to Mike, although if you intend to indict him for not admitting something simple, you have to really show that it’s simple. I think the whole hammering on Mike to admit is a dry effort anyway. Better to argue the contamination issue, itself. Think about it this way, if you had that LANL director, me, Huybers, Curry, Huybers, Zorita, etc. and you wanted them to sign off that this thing was a slam dunk. they might want to really see that it was a slam dunk.

Little story: I remember Peilke and Boris(?) having some argument about some IPCC definition and if it was a mistake. And they were both all hot and bothered with each other and EACH thought he was not just right, but OBVIOUSLY right. And I read it real quick and certainly could not tell just from the blog debate who was right. I knew that I would have to read the source documents that they spoke of, maybe even have some context from being in the field to rule on who was right. So even though both thought it was crushingly obvious and not really even debatable, I couldn’t judge so quick. Well, maybe I’m dumb or wishywashy or something. But then an interesting thing happened. Zorita was appealed to (by Boris, I think, but no matter) to rule on the dispute. And I asked him to rule as well. Not because I think he needs to adjuticate all disputes. But because if it really were simple, he could do so quickly. Now this is a guy who has decades of climate science working exerience. And guess what he said…basically, what a bother, I’ll have to go read all the documents…it’s not obvious just from you two antagonists arguing in a blog.

Anyway…I think disconnecting the “what is correct science” from the “Mike fails to admit” (and not wasting toooo much time on the latter) is both better tactically for dealing with the Po-Mo scientist as an opponent AND better for the disinterested observer who cares about science.

—————-
I was gonna reply to the reviewer comment, but I didn’t have anything additive to say over previous.

(Partisan) description: The authors studied the isotopic composition of carbon (δ13C) and hydrogen (δD) in organic matter found in two sediment cores retrieved from Lake Korttajarvi. They found that “the Medieval Warm Period in AD 980-1250 is associated with a local maximum in δD, lending support for a significant warming during that time.” Researchers generally find “δD increasing at warmer environmental conditions.”

Is Tiljander on to something with these metrics, or is this (another) reach? Don’t know, I’m traveling and can’t pull the paper for a while.

Isotopic effects seem like a good temp proxy. maybe more so with ice with the fractionation and all (but I’m reaching myself now).

I’m all in favor of extracting more information from the core by chemical analyses.

I worry a little about Tiljander taking noise and comparing to other studies, but if we assemble all her work (maybe even all the references she has) together, I might be more charitable. I’m not an expert and my first look at something tends to be critical.

I won’t be able to get into library either for a while. Your note reminds me though, that we really ought to pull the other two non-Boreas Tiljander papers that made up her thesis. (Is this one of those?) Also, there is the unpublished Aulanias population growth reference…and really just pulling all the references for Tiljander. I know it sounds like overkill, but that’s they way I’ve rolled in the past.

In the wake of this thread, my feeling is that Tiljander03 comparisons will fill in a lot of blanks, very possibly outlining superior methods for looking at varved-sediments and extracting climate proxies (isotopes, etc.).

It will be interesting. At the moment, I can’t see it rescuing Tiljander03’s four data series from the point of view of Mann08’s methods. Kaufman09 and their splice-calibration method, ok, something to talk about. But Mann08 is stuck with asserting that their direct 1850-1995 calibration is sensible. Recent decades’ parabolic data climb and all. They need a theory, bad, and at the moment I don’t even see a fig leaf.

On the other hand, wouldn’t it be cool to dig up (heh) some series like Luoto’s that really do look like proxies!

The recent Frank, Esper, Zorita, Wilson paper on reconstructions is interesting, where they talk about the preference for using a few good proxies and not using hundreds of proxies and doing complex math. It kinda fits with my comments that the team was heavy on tree-ring expertise and maybe could do some quality control based on that (with Hughes there), but should have maybe had a varve expert (or a cavesickle expert too). The other aspect to this (and maybe MikeN’s “the code didn’t flip” points are similar) is that Mann was just feeding stuff into the proxyhopper. He was basically treating Tiljander like everything else. so, then you have to challenge is that the right way to treat things, where else are their problems, etc. But it’s a subtley different point than deliberately using something you knew was flawed. Maybe, he thinks all the stuff is messed up and the proxyhopper can grind and get a good result.

And even though I lean to the Frank point of view, I think it’s kinda good that one person (Mike) is trying the proxyhopperish approach. It’s just that instead of so much ego-publishing in PNAS/Nature/Science and so much emphasis on the answer (the recon) and in backing up his earlier work, it out to be explored as an approach that may extract signal out of noise.

Following on from that, I really disliked how the paper had the sensitivity tests in the SI and the discussion of proxy quality in the SI. It should have been front and center. IOW, explain WHAT enabled them to go back further in time, WHAT enabled them to do the tree-less tests and then also discuss the qualities of those new proxies (geo-coverage, different confounders as opposed to trees, wuotes from papers, etc.).

I also didn’t like the having both CPS and EIV in the paper, unless they were really going to do a full factorial and show all the results wrt methodology. For instance, the discuss doing EIV with various variations (local gridcell, global, etc.). All the permutations of data and methodology choices would make more sense.

I haven’t studied Luoto in detail (really need to print this stuff off to make it easier, printer broken). The Zorita paper seems to say that the LIA has less evidence for it than the MWP (although perhaps they mean globablly, I’m not sure if it has very strong evidence as a regional effect).